diff --git a/eslint.config.mjs b/eslint.config.mjs
index 484d418ca5..195a9799f6 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1,6 +1,7 @@
 import js from "@eslint/js";
 import typescriptEslint from "@typescript-eslint/eslint-plugin";
 import importt from "eslint-plugin-import";
+// eslint-disable-next-line import/extensions
 import prettier from "eslint-plugin-prettier/recommended";
 import simpleImportSort from "eslint-plugin-simple-import-sort";
 import globals from "globals";
@@ -58,6 +59,8 @@ export default [
         },
       ],
 
+      "import/extensions": ["warn", "ignorePackages"],
+
       "simple-import-sort/imports": "warn",
       "simple-import-sort/exports": "warn",
     },
diff --git a/packages/amino/src/addresses.spec.ts b/packages/amino/src/addresses.spec.ts
index 4b1735d4f1..ee137a8b7b 100644
--- a/packages/amino/src/addresses.spec.ts
+++ b/packages/amino/src/addresses.spec.ts
@@ -1,8 +1,8 @@
 import { fromBech32, fromHex, toBase64 } from "@cosmjs/encoding";
 
-import { pubkeyToAddress, pubkeyToRawAddress } from "./addresses";
-import { decodeBech32Pubkey } from "./encoding";
-import { MultisigThresholdPubkey } from "./pubkeys";
+import { pubkeyToAddress, pubkeyToRawAddress } from "./addresses.ts";
+import { decodeBech32Pubkey } from "./encoding.ts";
+import { MultisigThresholdPubkey } from "./pubkeys.ts";
 
 describe("addresses", () => {
   describe("pubkeyToRawAddress", () => {
diff --git a/packages/amino/src/addresses.ts b/packages/amino/src/addresses.ts
index 71b39575eb..4c70436a7a 100644
--- a/packages/amino/src/addresses.ts
+++ b/packages/amino/src/addresses.ts
@@ -3,8 +3,8 @@
 import { ripemd160, sha256 } from "@cosmjs/crypto";
 import { fromBase64, toBech32 } from "@cosmjs/encoding";
 
-import { encodeAminoPubkey } from "./encoding";
-import { isEd25519Pubkey, isMultisigThresholdPubkey, isSecp256k1Pubkey, Pubkey } from "./pubkeys";
+import { encodeAminoPubkey } from "./encoding.ts";
+import { isEd25519Pubkey, isMultisigThresholdPubkey, isSecp256k1Pubkey, Pubkey } from "./pubkeys.ts";
 
 export function rawEd25519PubkeyToRawAddress(pubkeyData: Uint8Array): Uint8Array<ArrayBuffer> {
   if (pubkeyData.length !== 32) {
diff --git a/packages/amino/src/coins.spec.ts b/packages/amino/src/coins.spec.ts
index da2fd1d6a5..42d3b6ebb7 100644
--- a/packages/amino/src/coins.spec.ts
+++ b/packages/amino/src/coins.spec.ts
@@ -1,4 +1,4 @@
-import { addCoins, coin, coins, parseCoins } from "./coins";
+import { addCoins, coin, coins, parseCoins } from "./coins.ts";
 
 describe("coins", () => {
   describe("coin", () => {
diff --git a/packages/amino/src/encoding.spec.ts b/packages/amino/src/encoding.spec.ts
index 5cad53a55c..b4e301126b 100644
--- a/packages/amino/src/encoding.spec.ts
+++ b/packages/amino/src/encoding.spec.ts
@@ -8,8 +8,8 @@ import {
   encodeBech32Pubkey,
   encodeEd25519Pubkey,
   encodeSecp256k1Pubkey,
-} from "./encoding";
-import { Pubkey } from "./pubkeys";
+} from "./encoding.ts";
+import { Pubkey } from "./pubkeys.ts";
 import {
   testgroup1,
   testgroup1PubkeyBech32,
@@ -19,7 +19,7 @@ import {
   testgroup3PubkeyBech32,
   testgroup4,
   testgroup4PubkeyBech32,
-} from "./testutils";
+} from "./testutils.ts";
 
 describe("encoding", () => {
   describe("encodeSecp256k1Pubkey", () => {
diff --git a/packages/amino/src/encoding.ts b/packages/amino/src/encoding.ts
index 950c77dc5c..94599eb7cd 100644
--- a/packages/amino/src/encoding.ts
+++ b/packages/amino/src/encoding.ts
@@ -11,7 +11,7 @@ import {
   Pubkey,
   pubkeyType,
   Secp256k1Pubkey,
-} from "./pubkeys";
+} from "./pubkeys.ts";
 
 /**
  * Takes a Secp256k1 public key as raw bytes and returns the Amino JSON
diff --git a/packages/amino/src/index.ts b/packages/amino/src/index.ts
index 2c8f866a7f..8021901153 100644
--- a/packages/amino/src/index.ts
+++ b/packages/amino/src/index.ts
@@ -3,9 +3,9 @@ export {
   pubkeyToRawAddress,
   rawEd25519PubkeyToRawAddress,
   rawSecp256k1PubkeyToRawAddress,
-} from "./addresses";
-export type { Coin } from "./coins";
-export { addCoins, coin, coins, parseCoins } from "./coins";
+} from "./addresses.ts";
+export type { Coin } from "./coins.ts";
+export { addCoins, coin, coins, parseCoins } from "./coins.ts";
 export {
   decodeAminoPubkey,
   decodeBech32Pubkey,
@@ -13,33 +13,33 @@ export {
   encodeBech32Pubkey,
   encodeEd25519Pubkey,
   encodeSecp256k1Pubkey,
-} from "./encoding";
-export { createMultisigThresholdPubkey } from "./multisig";
-export { omitDefault } from "./omitdefault";
-export { makeCosmoshubPath } from "./paths";
+} from "./encoding.ts";
+export { createMultisigThresholdPubkey } from "./multisig.ts";
+export { omitDefault } from "./omitdefault.ts";
+export { makeCosmoshubPath } from "./paths.ts";
 export type {
   Ed25519Pubkey,
   MultisigThresholdPubkey,
   Pubkey,
   Secp256k1Pubkey,
   SinglePubkey,
-} from "./pubkeys";
+} from "./pubkeys.ts";
 export {
   isEd25519Pubkey,
   isMultisigThresholdPubkey,
   isSecp256k1Pubkey,
   isSinglePubkey,
   pubkeyType,
-} from "./pubkeys";
+} from "./pubkeys.ts";
 export {
   type Secp256k1HdWalletOptions,
   extractKdfConfiguration,
   Secp256k1HdWallet,
-} from "./secp256k1hdwallet";
-export { Secp256k1Wallet } from "./secp256k1wallet";
-export { type StdSignature, decodeSignature, encodeSecp256k1Signature } from "./signature";
-export type { AminoMsg, StdFee, StdSignDoc } from "./signdoc";
-export { makeSignDoc, serializeSignDoc } from "./signdoc";
-export type { AccountData, Algo, AminoSignResponse, OfflineAminoSigner } from "./signer";
-export { type StdTx, isStdTx, makeStdTx } from "./stdtx";
-export { type KdfConfiguration, executeKdf } from "./wallet";
+} from "./secp256k1hdwallet.ts";
+export { Secp256k1Wallet } from "./secp256k1wallet.ts";
+export { type StdSignature, decodeSignature, encodeSecp256k1Signature } from "./signature.ts";
+export type { AminoMsg, StdFee, StdSignDoc } from "./signdoc.ts";
+export { makeSignDoc, serializeSignDoc } from "./signdoc.ts";
+export type { AccountData, Algo, AminoSignResponse, OfflineAminoSigner } from "./signer.ts";
+export { type StdTx, isStdTx, makeStdTx } from "./stdtx.ts";
+export { type KdfConfiguration, executeKdf } from "./wallet.ts";
diff --git a/packages/amino/src/multisig.spec.ts b/packages/amino/src/multisig.spec.ts
index 965dc389e8..4f015c81d7 100644
--- a/packages/amino/src/multisig.spec.ts
+++ b/packages/amino/src/multisig.spec.ts
@@ -1,5 +1,5 @@
-import { compareArrays, createMultisigThresholdPubkey } from "./multisig";
-import { test1, test2, test3, testgroup1, testgroup2, testgroup3, testgroup4 } from "./testutils";
+import { compareArrays, createMultisigThresholdPubkey } from "./multisig.ts";
+import { test1, test2, test3, testgroup1, testgroup2, testgroup3, testgroup4 } from "./testutils.ts";
 
 describe("multisig", () => {
   describe("compareArrays", () => {
diff --git a/packages/amino/src/multisig.ts b/packages/amino/src/multisig.ts
index 7e8ecc5a22..ddc69092dd 100644
--- a/packages/amino/src/multisig.ts
+++ b/packages/amino/src/multisig.ts
@@ -1,8 +1,8 @@
 import { toHex } from "@cosmjs/encoding";
 import { Uint53 } from "@cosmjs/math";
 
-import { pubkeyToRawAddress } from "./addresses";
-import { MultisigThresholdPubkey, SinglePubkey } from "./pubkeys";
+import { pubkeyToRawAddress } from "./addresses.ts";
+import { MultisigThresholdPubkey, SinglePubkey } from "./pubkeys.ts";
 
 /**
  * Compare arrays lexicographically.
diff --git a/packages/amino/src/omitdefault.spec.ts b/packages/amino/src/omitdefault.spec.ts
index de82d76f0d..1a924948cb 100644
--- a/packages/amino/src/omitdefault.spec.ts
+++ b/packages/amino/src/omitdefault.spec.ts
@@ -1,4 +1,4 @@
-import { omitDefault } from "./omitdefault";
+import { omitDefault } from "./omitdefault.ts";
 
 describe("omitDefault", () => {
   it("works for numbers", () => {
diff --git a/packages/amino/src/paths.spec.ts b/packages/amino/src/paths.spec.ts
index 17fd85b6f8..6547465688 100644
--- a/packages/amino/src/paths.spec.ts
+++ b/packages/amino/src/paths.spec.ts
@@ -1,6 +1,6 @@
 import { Slip10RawIndex } from "@cosmjs/crypto";
 
-import { makeCosmoshubPath } from "./paths";
+import { makeCosmoshubPath } from "./paths.ts";
 
 describe("paths", () => {
   describe("makeCosmoshubPath", () => {
diff --git a/packages/amino/src/pubkeys.spec.ts b/packages/amino/src/pubkeys.spec.ts
index ec47bdcb3d..c8c59aa2cf 100644
--- a/packages/amino/src/pubkeys.spec.ts
+++ b/packages/amino/src/pubkeys.spec.ts
@@ -1,4 +1,4 @@
-import { isMultisigThresholdPubkey, isSinglePubkey } from "./pubkeys";
+import { isMultisigThresholdPubkey, isSinglePubkey } from "./pubkeys.ts";
 
 describe("pubkeys", () => {
   const pubkeyEd25519 = {
diff --git a/packages/amino/src/secp256k1hdwallet.spec.ts b/packages/amino/src/secp256k1hdwallet.spec.ts
index 074b0b9ecc..8bb57338e2 100644
--- a/packages/amino/src/secp256k1hdwallet.spec.ts
+++ b/packages/amino/src/secp256k1hdwallet.spec.ts
@@ -1,11 +1,11 @@
 import { Secp256k1, Secp256k1Signature, sha256 } from "@cosmjs/crypto";
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { makeCosmoshubPath } from "./paths";
-import { extractKdfConfiguration, Secp256k1HdWallet } from "./secp256k1hdwallet";
-import { serializeSignDoc, StdSignDoc } from "./signdoc";
-import { base64Matcher } from "./testutils";
-import { executeKdf, KdfConfiguration } from "./wallet";
+import { makeCosmoshubPath } from "./paths.ts";
+import { extractKdfConfiguration, Secp256k1HdWallet } from "./secp256k1hdwallet.ts";
+import { serializeSignDoc, StdSignDoc } from "./signdoc.ts";
+import { base64Matcher } from "./testutils.ts";
+import { executeKdf, KdfConfiguration } from "./wallet.ts";
 
 describe("Secp256k1HdWallet", () => {
   // m/44'/118'/0'/0/0
diff --git a/packages/amino/src/secp256k1hdwallet.ts b/packages/amino/src/secp256k1hdwallet.ts
index 44e830e257..2c10b23cdb 100644
--- a/packages/amino/src/secp256k1hdwallet.ts
+++ b/packages/amino/src/secp256k1hdwallet.ts
@@ -14,11 +14,11 @@ import {
 import { fromBase64, fromUtf8, toBase64, toBech32, toUtf8 } from "@cosmjs/encoding";
 import { assert, isNonNullObject } from "@cosmjs/utils";
 
-import { rawSecp256k1PubkeyToRawAddress } from "./addresses";
-import { makeCosmoshubPath } from "./paths";
-import { encodeSecp256k1Signature } from "./signature";
-import { serializeSignDoc, StdSignDoc } from "./signdoc";
-import { AccountData, AminoSignResponse, OfflineAminoSigner } from "./signer";
+import { rawSecp256k1PubkeyToRawAddress } from "./addresses.ts";
+import { makeCosmoshubPath } from "./paths.ts";
+import { encodeSecp256k1Signature } from "./signature.ts";
+import { serializeSignDoc, StdSignDoc } from "./signdoc.ts";
+import { AccountData, AminoSignResponse, OfflineAminoSigner } from "./signer.ts";
 import {
   decrypt,
   encrypt,
@@ -26,7 +26,7 @@ import {
   executeKdf,
   KdfConfiguration,
   supportedAlgorithms,
-} from "./wallet";
+} from "./wallet.ts";
 
 interface AccountDataWithPrivkey extends AccountData {
   readonly privkey: Uint8Array;
diff --git a/packages/amino/src/secp256k1wallet.spec.ts b/packages/amino/src/secp256k1wallet.spec.ts
index 467cafa046..f119dfc37d 100644
--- a/packages/amino/src/secp256k1wallet.spec.ts
+++ b/packages/amino/src/secp256k1wallet.spec.ts
@@ -1,8 +1,8 @@
 import { Secp256k1, Secp256k1Signature, Sha256 } from "@cosmjs/crypto";
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { Secp256k1Wallet } from "./secp256k1wallet";
-import { serializeSignDoc, StdSignDoc } from "./signdoc";
+import { Secp256k1Wallet } from "./secp256k1wallet.ts";
+import { serializeSignDoc, StdSignDoc } from "./signdoc.ts";
 
 describe("Secp256k1Wallet", () => {
   const defaultPrivkey = fromHex("b8c462d2bb0c1a92edf44f735021f16c270f28ee2c3d1cb49943a5e70a3c763e");
diff --git a/packages/amino/src/secp256k1wallet.ts b/packages/amino/src/secp256k1wallet.ts
index 0f8a3f3bb1..5ed2781ef5 100644
--- a/packages/amino/src/secp256k1wallet.ts
+++ b/packages/amino/src/secp256k1wallet.ts
@@ -1,10 +1,10 @@
 import { Secp256k1, Sha256 } from "@cosmjs/crypto";
 import { toBech32 } from "@cosmjs/encoding";
 
-import { rawSecp256k1PubkeyToRawAddress } from "./addresses";
-import { encodeSecp256k1Signature } from "./signature";
-import { serializeSignDoc, StdSignDoc } from "./signdoc";
-import { AccountData, AminoSignResponse, OfflineAminoSigner } from "./signer";
+import { rawSecp256k1PubkeyToRawAddress } from "./addresses.ts";
+import { encodeSecp256k1Signature } from "./signature.ts";
+import { serializeSignDoc, StdSignDoc } from "./signdoc.ts";
+import { AccountData, AminoSignResponse, OfflineAminoSigner } from "./signer.ts";
 
 /**
  * A wallet that holds a single secp256k1 keypair.
diff --git a/packages/amino/src/signature.spec.ts b/packages/amino/src/signature.spec.ts
index d28c9c885a..96582d8ce0 100644
--- a/packages/amino/src/signature.spec.ts
+++ b/packages/amino/src/signature.spec.ts
@@ -1,6 +1,6 @@
 import { fromBase64 } from "@cosmjs/encoding";
 
-import { decodeSignature, encodeSecp256k1Signature, StdSignature } from "./signature";
+import { decodeSignature, encodeSecp256k1Signature, StdSignature } from "./signature.ts";
 
 describe("signature", () => {
   describe("encodeSecp256k1Signature", () => {
diff --git a/packages/amino/src/signature.ts b/packages/amino/src/signature.ts
index cea95b014b..c24de06241 100644
--- a/packages/amino/src/signature.ts
+++ b/packages/amino/src/signature.ts
@@ -1,8 +1,8 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { fromBase64, toBase64 } from "@cosmjs/encoding";
 
-import { encodeSecp256k1Pubkey } from "./encoding";
-import { Pubkey, pubkeyType } from "./pubkeys";
+import { encodeSecp256k1Pubkey } from "./encoding.ts";
+import { Pubkey, pubkeyType } from "./pubkeys.ts";
 
 export interface StdSignature {
   readonly pub_key: Pubkey;
diff --git a/packages/amino/src/signdoc.spec.ts b/packages/amino/src/signdoc.spec.ts
index 10b4e2a5f4..8389ea4786 100644
--- a/packages/amino/src/signdoc.spec.ts
+++ b/packages/amino/src/signdoc.spec.ts
@@ -1,7 +1,7 @@
 import { Random } from "@cosmjs/crypto";
 import { toBech32 } from "@cosmjs/encoding";
 
-import { AminoMsg, escapeCharacters, makeSignDoc, sortedJsonStringify } from "./signdoc";
+import { AminoMsg, escapeCharacters, makeSignDoc, sortedJsonStringify } from "./signdoc.ts";
 
 function makeRandomAddress(): string {
   return toBech32("cosmos", Random.getBytes(20));
diff --git a/packages/amino/src/signdoc.ts b/packages/amino/src/signdoc.ts
index 91ba4cffd0..abb5af48c1 100644
--- a/packages/amino/src/signdoc.ts
+++ b/packages/amino/src/signdoc.ts
@@ -2,7 +2,7 @@
 import { toUtf8 } from "@cosmjs/encoding";
 import { Uint53 } from "@cosmjs/math";
 
-import { Coin } from "./coins";
+import { Coin } from "./coins.ts";
 
 export interface AminoMsg {
   readonly type: string;
diff --git a/packages/amino/src/signer.ts b/packages/amino/src/signer.ts
index 89de5a2763..33d6b76264 100644
--- a/packages/amino/src/signer.ts
+++ b/packages/amino/src/signer.ts
@@ -1,5 +1,5 @@
-import { StdSignature } from "./signature";
-import { StdSignDoc } from "./signdoc";
+import { StdSignature } from "./signature.ts";
+import { StdSignDoc } from "./signdoc.ts";
 
 export type Algo = "secp256k1" | "ed25519" | "sr25519";
 
diff --git a/packages/amino/src/stdtx.spec.ts b/packages/amino/src/stdtx.spec.ts
index a625eeeb0f..f71771741d 100644
--- a/packages/amino/src/stdtx.spec.ts
+++ b/packages/amino/src/stdtx.spec.ts
@@ -1,7 +1,7 @@
-import { coins } from "./coins";
-import { StdSignature } from "./signature";
-import { makeSignDoc, StdFee } from "./signdoc";
-import { isStdTx, makeStdTx, StdTx } from "./stdtx";
+import { coins } from "./coins.ts";
+import { StdSignature } from "./signature.ts";
+import { makeSignDoc, StdFee } from "./signdoc.ts";
+import { isStdTx, makeStdTx, StdTx } from "./stdtx.ts";
 
 describe("makeStdTx", () => {
   it("can make an StdTx from a SignDoc and one signature", () => {
diff --git a/packages/amino/src/stdtx.ts b/packages/amino/src/stdtx.ts
index 2948e1fa9d..0559bd76ad 100644
--- a/packages/amino/src/stdtx.ts
+++ b/packages/amino/src/stdtx.ts
@@ -1,5 +1,5 @@
-import { StdSignature } from "./signature";
-import { AminoMsg, StdFee, StdSignDoc } from "./signdoc";
+import { StdSignature } from "./signature.ts";
+import { AminoMsg, StdFee, StdSignDoc } from "./signdoc.ts";
 
 /**
  * A Cosmos SDK StdTx
diff --git a/packages/amino/src/testutils.ts b/packages/amino/src/testutils.ts
index c506998c95..0873afb0f8 100644
--- a/packages/amino/src/testutils.ts
+++ b/packages/amino/src/testutils.ts
@@ -1,5 +1,5 @@
-import { decodeBech32Pubkey } from "./encoding";
-import { MultisigThresholdPubkey } from "./pubkeys";
+import { decodeBech32Pubkey } from "./encoding.ts";
+import { MultisigThresholdPubkey } from "./pubkeys.ts";
 
 export const base64Matcher =
   /^(?:[a-zA-Z0-9+/]{4})*(?:|(?:[a-zA-Z0-9+/]{3}=)|(?:[a-zA-Z0-9+/]{2}==)|(?:[a-zA-Z0-9+/]{1}===))$/;
diff --git a/packages/cosmwasm/src/compression.spec.ts b/packages/cosmwasm/src/compression.spec.ts
index 0e842d48fa..ee6d7fa5ca 100644
--- a/packages/cosmwasm/src/compression.spec.ts
+++ b/packages/cosmwasm/src/compression.spec.ts
@@ -1,7 +1,7 @@
 import { fromHex } from "@cosmjs/encoding";
 import { Uint32 } from "@cosmjs/math";
 
-import { gzip } from "./compression";
+import { gzip } from "./compression.ts";
 
 async function uncompress(compressed: Uint8Array): Promise<Uint8Array> {
   const ds = new DecompressionStream("gzip");
diff --git a/packages/cosmwasm/src/cosmwasmclient.searchtx.spec.ts b/packages/cosmwasm/src/cosmwasmclient.searchtx.spec.ts
index ad2bf8fb39..b5e7c97e8b 100644
--- a/packages/cosmwasm/src/cosmwasmclient.searchtx.spec.ts
+++ b/packages/cosmwasm/src/cosmwasmclient.searchtx.spec.ts
@@ -19,8 +19,8 @@ import {
 import { assert, sleep } from "@cosmjs/utils";
 import { TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { CosmWasmClient } from "./cosmwasmclient";
-import { alice, fromOneElementArray, makeRandomAddress, wasmd, wasmdEnabled } from "./testutils";
+import { CosmWasmClient } from "./cosmwasmclient.ts";
+import { alice, fromOneElementArray, makeRandomAddress, wasmd, wasmdEnabled } from "./testutils.ts";
 
 interface TestTxSend {
   readonly sender: string;
diff --git a/packages/cosmwasm/src/cosmwasmclient.spec.ts b/packages/cosmwasm/src/cosmwasmclient.spec.ts
index 150b60ff06..bf2264916b 100644
--- a/packages/cosmwasm/src/cosmwasmclient.spec.ts
+++ b/packages/cosmwasm/src/cosmwasmclient.spec.ts
@@ -14,8 +14,8 @@ import { assert, sleep } from "@cosmjs/utils";
 import { TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { ReadonlyDate } from "readonly-date";
 
-import { Code, CosmWasmClient, PrivateCosmWasmClient } from "./cosmwasmclient";
-import { SigningCosmWasmClient } from "./signingcosmwasmclient";
+import { Code, CosmWasmClient, PrivateCosmWasmClient } from "./cosmwasmclient.ts";
+import { SigningCosmWasmClient } from "./signingcosmwasmclient.ts";
 import {
   alice,
   defaultInstantiateFee,
@@ -28,7 +28,7 @@ import {
   unused,
   wasmd,
   wasmdEnabled,
-} from "./testutils";
+} from "./testutils.ts";
 
 interface HackatomInstance {
   readonly instantiateMsg: {
diff --git a/packages/cosmwasm/src/cosmwasmclient.ts b/packages/cosmwasm/src/cosmwasmclient.ts
index 06ac6f9fdc..6520ba1012 100644
--- a/packages/cosmwasm/src/cosmwasmclient.ts
+++ b/packages/cosmwasm/src/cosmwasmclient.ts
@@ -32,7 +32,7 @@ import {
 } from "cosmjs-types/cosmwasm/wasm/v1/query";
 import { ContractCodeHistoryOperationType } from "cosmjs-types/cosmwasm/wasm/v1/types";
 
-import { JsonObject, setupWasmExtension, WasmExtension } from "./modules";
+import { JsonObject, setupWasmExtension, WasmExtension } from "./modules/index.ts";
 
 export interface Code {
   readonly id: number;
diff --git a/packages/cosmwasm/src/encoding.spec.ts b/packages/cosmwasm/src/encoding.spec.ts
index 58972deccf..6f4810e5fb 100644
--- a/packages/cosmwasm/src/encoding.spec.ts
+++ b/packages/cosmwasm/src/encoding.spec.ts
@@ -1,4 +1,4 @@
-import { fromBinary, toBinary } from "./encoding";
+import { fromBinary, toBinary } from "./encoding.ts";
 
 describe("encoding", () => {
   describe("toBinary", () => {
diff --git a/packages/cosmwasm/src/index.ts b/packages/cosmwasm/src/index.ts
index c052f31a72..05163f0ddc 100644
--- a/packages/cosmwasm/src/index.ts
+++ b/packages/cosmwasm/src/index.ts
@@ -1,7 +1,7 @@
-export type { Code, CodeDetails, Contract, ContractCodeHistoryEntry } from "./cosmwasmclient";
-export { CosmWasmClient } from "./cosmwasmclient";
-export { fromBinary, toBinary } from "./encoding";
-export { _instantiate2AddressIntermediate, instantiate2Address } from "./instantiate2";
+export type { Code, CodeDetails, Contract, ContractCodeHistoryEntry } from "./cosmwasmclient.ts";
+export { CosmWasmClient } from "./cosmwasmclient.ts";
+export { fromBinary, toBinary } from "./encoding.ts";
+export { _instantiate2AddressIntermediate, instantiate2Address } from "./instantiate2.ts";
 export type {
   JsonObject,
   MsgClearAdminEncodeObject,
@@ -12,7 +12,7 @@ export type {
   MsgStoreCodeEncodeObject,
   MsgUpdateAdminEncodeObject,
   WasmExtension,
-} from "./modules";
+} from "./modules/index.ts";
 export {
   createWasmAminoConverters,
   isMsgClearAdminEncodeObject,
@@ -24,7 +24,7 @@ export {
   isMsgUpdateAdminEncodeObject,
   setupWasmExtension,
   wasmTypes,
-} from "./modules";
+} from "./modules/index.ts";
 export type {
   ChangeAdminResult,
   ExecuteInstruction,
@@ -34,8 +34,8 @@ export type {
   MigrateResult,
   SigningCosmWasmClientOptions,
   UploadResult,
-} from "./signingcosmwasmclient";
-export { SigningCosmWasmClient } from "./signingcosmwasmclient";
+} from "./signingcosmwasmclient.ts";
+export { SigningCosmWasmClient } from "./signingcosmwasmclient.ts";
 
 // Re-exported because this is part of the CosmWasmClient/SigningCosmWasmClient APIs
 export type { Attribute, DeliverTxResponse, Event, IndexedTx } from "@cosmjs/stargate";
diff --git a/packages/cosmwasm/src/instantiate2.spec.ts b/packages/cosmwasm/src/instantiate2.spec.ts
index 571346e521..a17b17c748 100644
--- a/packages/cosmwasm/src/instantiate2.spec.ts
+++ b/packages/cosmwasm/src/instantiate2.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { instantiate2Address } from "./instantiate2";
+import { instantiate2Address } from "./instantiate2.ts";
 
 describe("instantiate2", () => {
   describe("instantiate2Address", () => {
diff --git a/packages/cosmwasm/src/modules/index.ts b/packages/cosmwasm/src/modules/index.ts
index f20f1d06e8..ba1c213a9b 100644
--- a/packages/cosmwasm/src/modules/index.ts
+++ b/packages/cosmwasm/src/modules/index.ts
@@ -5,8 +5,8 @@ export type {
   AminoMsgMigrateContract,
   AminoMsgStoreCode,
   AminoMsgUpdateAdmin,
-} from "./wasm/aminomessages";
-export { createWasmAminoConverters } from "./wasm/aminomessages";
+} from "./wasm/aminomessages.ts";
+export { createWasmAminoConverters } from "./wasm/aminomessages.ts";
 export type {
   MsgClearAdminEncodeObject,
   MsgExecuteContractEncodeObject,
@@ -15,7 +15,7 @@ export type {
   MsgMigrateContractEncodeObject,
   MsgStoreCodeEncodeObject,
   MsgUpdateAdminEncodeObject,
-} from "./wasm/messages";
+} from "./wasm/messages.ts";
 export {
   isMsgClearAdminEncodeObject,
   isMsgExecuteEncodeObject,
@@ -25,6 +25,6 @@ export {
   isMsgStoreCodeEncodeObject,
   isMsgUpdateAdminEncodeObject,
   wasmTypes,
-} from "./wasm/messages";
-export type { JsonObject, WasmExtension } from "./wasm/queries";
-export { setupWasmExtension } from "./wasm/queries";
+} from "./wasm/messages.ts";
+export type { JsonObject, WasmExtension } from "./wasm/queries.ts";
+export { setupWasmExtension } from "./wasm/queries.ts";
diff --git a/packages/cosmwasm/src/modules/wasm/aminomessages.spec.ts b/packages/cosmwasm/src/modules/wasm/aminomessages.spec.ts
index 2a45d3d7ec..12216dd823 100644
--- a/packages/cosmwasm/src/modules/wasm/aminomessages.spec.ts
+++ b/packages/cosmwasm/src/modules/wasm/aminomessages.spec.ts
@@ -20,7 +20,7 @@ import {
   AminoMsgStoreCode,
   AminoMsgUpdateAdmin,
   createWasmAminoConverters,
-} from "./aminomessages";
+} from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("toAmino", () => {
diff --git a/packages/cosmwasm/src/modules/wasm/queries.spec.ts b/packages/cosmwasm/src/modules/wasm/queries.spec.ts
index 5157bdb9b8..4a0338d684 100644
--- a/packages/cosmwasm/src/modules/wasm/queries.spec.ts
+++ b/packages/cosmwasm/src/modules/wasm/queries.spec.ts
@@ -14,7 +14,7 @@ import { assert, assertDefined } from "@cosmjs/utils";
 import { MsgExecuteContract, MsgInstantiateContract, MsgStoreCode } from "cosmjs-types/cosmwasm/wasm/v1/tx";
 import { AbsoluteTxPosition, ContractCodeHistoryOperationType } from "cosmjs-types/cosmwasm/wasm/v1/types";
 
-import { findAttribute, SigningCosmWasmClient } from "../../signingcosmwasmclient";
+import { findAttribute, SigningCosmWasmClient } from "../../signingcosmwasmclient.ts";
 import {
   alice,
   bech32AddressMatcher,
@@ -25,14 +25,14 @@ import {
   makeWasmClient,
   wasmd,
   wasmdEnabled,
-} from "../../testutils";
+} from "../../testutils.ts";
 import {
   MsgExecuteContractEncodeObject,
   MsgInstantiateContractEncodeObject,
   MsgStoreCodeEncodeObject,
   wasmTypes,
-} from "./messages";
-import { JsonObject } from "./queries";
+} from "./messages.ts";
+import { JsonObject } from "./queries.ts";
 
 const registry = new Registry(wasmTypes);
 
diff --git a/packages/cosmwasm/src/signingcosmwasmclient.spec.ts b/packages/cosmwasm/src/signingcosmwasmclient.spec.ts
index 1a0e07099d..d2bf3e211b 100644
--- a/packages/cosmwasm/src/signingcosmwasmclient.spec.ts
+++ b/packages/cosmwasm/src/signingcosmwasmclient.spec.ts
@@ -23,10 +23,10 @@ import { AuthInfo, TxBody, TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { MsgExecuteContract, MsgStoreCode } from "cosmjs-types/cosmwasm/wasm/v1/tx";
 import { AccessConfig, AccessType } from "cosmjs-types/cosmwasm/wasm/v1/types";
 
-import { gzip } from "./compression";
-import { instantiate2Address } from "./instantiate2";
-import { MsgExecuteContractEncodeObject, MsgStoreCodeEncodeObject } from "./modules";
-import { SigningCosmWasmClient, SigningCosmWasmClientOptions } from "./signingcosmwasmclient";
+import { gzip } from "./compression.ts";
+import { instantiate2Address } from "./instantiate2.ts";
+import { MsgExecuteContractEncodeObject, MsgStoreCodeEncodeObject } from "./modules/index.ts";
+import { SigningCosmWasmClient, SigningCosmWasmClientOptions } from "./signingcosmwasmclient.ts";
 import {
   alice,
   defaultClearAdminFee,
@@ -48,7 +48,7 @@ import {
   validator,
   wasmd,
   wasmdEnabled,
-} from "./testutils";
+} from "./testutils.ts";
 
 (wasmdEnabled ? describe : xdescribe)("SigningCosmWasmClient", () => {
   describe("connectWithSigner", () => {
diff --git a/packages/cosmwasm/src/signingcosmwasmclient.ts b/packages/cosmwasm/src/signingcosmwasmclient.ts
index 48eb4855de..2d42b3745f 100644
--- a/packages/cosmwasm/src/signingcosmwasmclient.ts
+++ b/packages/cosmwasm/src/signingcosmwasmclient.ts
@@ -48,8 +48,8 @@ import {
 } from "cosmjs-types/cosmwasm/wasm/v1/tx";
 import { AccessConfig } from "cosmjs-types/cosmwasm/wasm/v1/types";
 
-import { gzip } from "./compression";
-import { CosmWasmClient } from "./cosmwasmclient";
+import { gzip } from "./compression.ts";
+import { CosmWasmClient } from "./cosmwasmclient.ts";
 import {
   createWasmAminoConverters,
   JsonObject,
@@ -61,7 +61,7 @@ import {
   MsgStoreCodeEncodeObject,
   MsgUpdateAdminEncodeObject,
   wasmTypes,
-} from "./modules";
+} from "./modules/index.ts";
 
 export interface UploadResult {
   /** A hex encoded sha256 checksum of the original Wasm code (that is stored on chain) */
diff --git a/packages/cosmwasm/src/testutils.ts b/packages/cosmwasm/src/testutils.ts
index 25638c79bd..53f43db9da 100644
--- a/packages/cosmwasm/src/testutils.ts
+++ b/packages/cosmwasm/src/testutils.ts
@@ -22,8 +22,8 @@ import { assertDefinedAndNotNull } from "@cosmjs/utils";
 import { SignMode } from "cosmjs-types/cosmos/tx/signing/v1beta1/signing";
 import { AuthInfo, SignDoc, TxBody } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { setupWasmExtension, WasmExtension } from "./modules";
-import { SigningCosmWasmClientOptions } from "./signingcosmwasmclient";
+import { setupWasmExtension, WasmExtension } from "./modules/index.ts";
+import { SigningCosmWasmClientOptions } from "./signingcosmwasmclient.ts";
 import hackatom from "./testdata/contract.json";
 
 export const defaultGasPrice = GasPrice.fromString("0.025ucosm");
diff --git a/packages/crypto/src/bip39.spec.ts b/packages/crypto/src/bip39.spec.ts
index 01bed59866..723d83ecdc 100644
--- a/packages/crypto/src/bip39.spec.ts
+++ b/packages/crypto/src/bip39.spec.ts
@@ -1,7 +1,7 @@
 import { fromAscii, fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { Bip39, EnglishMnemonic } from "./bip39";
-import { sha256 } from "./sha";
+import { Bip39, EnglishMnemonic } from "./bip39.ts";
+import { sha256 } from "./sha.ts";
 import bip39Vectors from "./testdata/bip39.json";
 import wordlists from "./testdata/bip39_wordlists.json";
 
diff --git a/packages/crypto/src/hmac.spec.ts b/packages/crypto/src/hmac.spec.ts
index 16729636fd..5c1b05cf3a 100644
--- a/packages/crypto/src/hmac.spec.ts
+++ b/packages/crypto/src/hmac.spec.ts
@@ -1,7 +1,7 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { Hmac } from "./hmac";
-import { Sha256, Sha512 } from "./sha";
+import { Hmac } from "./hmac.ts";
+import { Sha256, Sha512 } from "./sha.ts";
 
 describe("HMAC", () => {
   it("can perform HMAC(SHA256) according to Botan test vectors", () => {
diff --git a/packages/crypto/src/hmac.ts b/packages/crypto/src/hmac.ts
index 5841cc6e64..6f6b6130c0 100644
--- a/packages/crypto/src/hmac.ts
+++ b/packages/crypto/src/hmac.ts
@@ -1,6 +1,6 @@
 import { fixUint8Array } from "@cosmjs/encoding";
 
-import { HashFunction } from "./hash";
+import { HashFunction } from "./hash.ts";
 
 export class Hmac<H extends HashFunction> implements HashFunction {
   public readonly blockSize: number;
diff --git a/packages/crypto/src/index.ts b/packages/crypto/src/index.ts
index ffadf1b941..a177a4d3bd 100644
--- a/packages/crypto/src/index.ts
+++ b/packages/crypto/src/index.ts
@@ -1,7 +1,7 @@
-export { Bip39, EnglishMnemonic } from "./bip39";
-export type { HashFunction } from "./hash";
-export { Hmac } from "./hmac";
-export { Keccak256, keccak256 } from "./keccak";
+export { Bip39, EnglishMnemonic } from "./bip39.ts";
+export type { HashFunction } from "./hash.ts";
+export { Hmac } from "./hmac.ts";
+export { Keccak256, keccak256 } from "./keccak.ts";
 export {
   type Argon2idOptions,
   Argon2id,
@@ -10,13 +10,13 @@ export {
   isArgon2idOptions,
   xchacha20NonceLength,
   Xchacha20poly1305Ietf,
-} from "./libsodium";
-export { Random } from "./random";
-export { Ripemd160, ripemd160 } from "./ripemd";
-export { type Secp256k1Keypair, Secp256k1 } from "./secp256k1";
-export { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature";
-export { Sha256, sha256, Sha512, sha512 } from "./sha";
-export type { HdPath, Slip10Result } from "./slip10";
+} from "./libsodium.ts";
+export { Random } from "./random.ts";
+export { Ripemd160, ripemd160 } from "./ripemd.ts";
+export { type Secp256k1Keypair, Secp256k1 } from "./secp256k1.ts";
+export { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature.ts";
+export { Sha256, sha256, Sha512, sha512 } from "./sha.ts";
+export type { HdPath, Slip10Result } from "./slip10.ts";
 export {
   pathToString,
   Slip10,
@@ -24,4 +24,4 @@ export {
   slip10CurveFromString,
   Slip10RawIndex,
   stringToPath,
-} from "./slip10";
+} from "./slip10.ts";
diff --git a/packages/crypto/src/keccak.spec.ts b/packages/crypto/src/keccak.spec.ts
index 5284063e7b..830d1de424 100644
--- a/packages/crypto/src/keccak.spec.ts
+++ b/packages/crypto/src/keccak.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex, toHex } from "@cosmjs/encoding";
 
-import { Keccak256, keccak256 } from "./keccak";
+import { Keccak256, keccak256 } from "./keccak.ts";
 import keccakVectors from "./testdata/keccak.json";
 
 describe("Keccak256", () => {
diff --git a/packages/crypto/src/keccak.ts b/packages/crypto/src/keccak.ts
index 581573387f..bd57a73493 100644
--- a/packages/crypto/src/keccak.ts
+++ b/packages/crypto/src/keccak.ts
@@ -1,8 +1,8 @@
 import { fixUint8Array } from "@cosmjs/encoding";
 import { keccak_256 } from "@noble/hashes/sha3.js";
 
-import { HashFunction } from "./hash";
-import { toRealUint8Array } from "./utils";
+import { HashFunction } from "./hash.ts";
+import { toRealUint8Array } from "./utils.ts";
 
 export class Keccak256 implements HashFunction {
   public readonly blockSize = 512 / 8;
diff --git a/packages/crypto/src/libsodium.spec.ts b/packages/crypto/src/libsodium.spec.ts
index d86a9df163..89ce46f92c 100644
--- a/packages/crypto/src/libsodium.spec.ts
+++ b/packages/crypto/src/libsodium.spec.ts
@@ -1,7 +1,7 @@
 /* eslint-disable no-bitwise */
 import { fromHex, toAscii } from "@cosmjs/encoding";
 
-import { Argon2id, Argon2idOptions, Ed25519, Ed25519Keypair, Xchacha20poly1305Ietf } from "./libsodium";
+import { Argon2id, Argon2idOptions, Ed25519, Ed25519Keypair, Xchacha20poly1305Ietf } from "./libsodium.ts";
 
 describe("Libsodium", () => {
   describe("Argon2id", () => {
diff --git a/packages/crypto/src/pbkdf2.spec.ts b/packages/crypto/src/pbkdf2.spec.ts
index 4be9bc617d..224b3a31c3 100644
--- a/packages/crypto/src/pbkdf2.spec.ts
+++ b/packages/crypto/src/pbkdf2.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex, toAscii, toUtf8 } from "@cosmjs/encoding";
 
-import { getSubtle, pbkdf2Sha512, pbkdf2Sha512Noble, pbkdf2Sha512Subtle } from "./pbkdf2";
+import { getSubtle, pbkdf2Sha512, pbkdf2Sha512Noble, pbkdf2Sha512Subtle } from "./pbkdf2.ts";
 
 interface TestVector {
   secret: Uint8Array;
diff --git a/packages/crypto/src/random.spec.ts b/packages/crypto/src/random.spec.ts
index c5af21d7ae..df7a7d0bd4 100644
--- a/packages/crypto/src/random.spec.ts
+++ b/packages/crypto/src/random.spec.ts
@@ -1,6 +1,6 @@
 import { isUint8Array } from "@cosmjs/utils";
 
-import { Random } from "./random";
+import { Random } from "./random.ts";
 
 describe("Random", () => {
   it("returns an Uint8Array", () => {
diff --git a/packages/crypto/src/ripemd.spec.ts b/packages/crypto/src/ripemd.spec.ts
index 72fd2f8a3f..d10df6d33c 100644
--- a/packages/crypto/src/ripemd.spec.ts
+++ b/packages/crypto/src/ripemd.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { Ripemd160, ripemd160 } from "./ripemd";
+import { Ripemd160, ripemd160 } from "./ripemd.ts";
 import ripemdVectors from "./testdata/ripemd.json";
 
 describe("Ripemd160", () => {
diff --git a/packages/crypto/src/ripemd.ts b/packages/crypto/src/ripemd.ts
index 56d0cfdd97..861a080c2b 100644
--- a/packages/crypto/src/ripemd.ts
+++ b/packages/crypto/src/ripemd.ts
@@ -1,8 +1,8 @@
 import { fixUint8Array } from "@cosmjs/encoding";
 import { ripemd160 as nobleRipemd160 } from "@noble/hashes/legacy.js";
 
-import { HashFunction } from "./hash";
-import { toRealUint8Array } from "./utils";
+import { HashFunction } from "./hash.ts";
+import { toRealUint8Array } from "./utils.ts";
 
 export class Ripemd160 implements HashFunction {
   public readonly blockSize = 512 / 8;
diff --git a/packages/crypto/src/secp256k1.spec.ts b/packages/crypto/src/secp256k1.spec.ts
index cd1032e803..93b9efabf8 100644
--- a/packages/crypto/src/secp256k1.spec.ts
+++ b/packages/crypto/src/secp256k1.spec.ts
@@ -1,9 +1,9 @@
 /* eslint-disable no-bitwise */
 import { fromHex } from "@cosmjs/encoding";
 
-import { Secp256k1 } from "./secp256k1";
-import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature";
-import { sha256 } from "./sha";
+import { Secp256k1 } from "./secp256k1.ts";
+import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature.ts";
+import { sha256 } from "./sha.ts";
 
 describe("Secp256k1", () => {
   // How to generate Secp256k1 test vectors:
diff --git a/packages/crypto/src/secp256k1.ts b/packages/crypto/src/secp256k1.ts
index 917889ca62..261a482ff1 100644
--- a/packages/crypto/src/secp256k1.ts
+++ b/packages/crypto/src/secp256k1.ts
@@ -2,7 +2,7 @@ import { fixUint8Array, fromHex, toHex } from "@cosmjs/encoding";
 import { assert } from "@cosmjs/utils";
 import { secp256k1 } from "@noble/curves/secp256k1";
 
-import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature";
+import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature.ts";
 
 export interface Secp256k1Keypair {
   /** A 32 byte private key */
diff --git a/packages/crypto/src/secp256k1signature.spec.ts b/packages/crypto/src/secp256k1signature.spec.ts
index 7a362e71db..cd1c1a7d2a 100644
--- a/packages/crypto/src/secp256k1signature.spec.ts
+++ b/packages/crypto/src/secp256k1signature.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature";
+import { ExtendedSecp256k1Signature, Secp256k1Signature } from "./secp256k1signature.ts";
 
 describe("Secp256k1Signature", () => {
   describe("fromFixedLength", () => {
diff --git a/packages/crypto/src/sha.spec.ts b/packages/crypto/src/sha.spec.ts
index 311c259761..ce9556b9f9 100644
--- a/packages/crypto/src/sha.spec.ts
+++ b/packages/crypto/src/sha.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex, toHex } from "@cosmjs/encoding";
 
-import { Sha256, sha256 } from "./sha";
+import { Sha256, sha256 } from "./sha.ts";
 import shaVectors from "./testdata/sha.json";
 
 describe("Sha256", () => {
diff --git a/packages/crypto/src/sha.ts b/packages/crypto/src/sha.ts
index f033daaeb0..8f9b7a00fc 100644
--- a/packages/crypto/src/sha.ts
+++ b/packages/crypto/src/sha.ts
@@ -1,8 +1,8 @@
 import { fixUint8Array } from "@cosmjs/encoding";
 import { sha256 as nobleSha256, sha512 as nobleSha512 } from "@noble/hashes/sha2.js";
 
-import { HashFunction } from "./hash";
-import { toRealUint8Array } from "./utils";
+import { HashFunction } from "./hash.ts";
+import { toRealUint8Array } from "./utils.ts";
 
 export class Sha256 implements HashFunction {
   public readonly blockSize = 512 / 8;
diff --git a/packages/crypto/src/slip10.spec.ts b/packages/crypto/src/slip10.spec.ts
index 7dc725659e..f66337cf4a 100644
--- a/packages/crypto/src/slip10.spec.ts
+++ b/packages/crypto/src/slip10.spec.ts
@@ -8,7 +8,7 @@ import {
   slip10CurveFromString,
   Slip10RawIndex,
   stringToPath,
-} from "./slip10";
+} from "./slip10.ts";
 
 describe("Slip10", () => {
   it("has working slip10CurveFromString()", () => {
diff --git a/packages/crypto/src/slip10.ts b/packages/crypto/src/slip10.ts
index 33fcca567b..ebe166e812 100644
--- a/packages/crypto/src/slip10.ts
+++ b/packages/crypto/src/slip10.ts
@@ -3,8 +3,8 @@ import { Uint32, Uint53 } from "@cosmjs/math";
 import { assert } from "@cosmjs/utils";
 import { secp256k1 } from "@noble/curves/secp256k1";
 
-import { Hmac } from "./hmac";
-import { Sha512 } from "./sha";
+import { Hmac } from "./hmac.ts";
+import { Sha512 } from "./sha.ts";
 
 export interface Slip10Result {
   readonly chainCode: Uint8Array;
diff --git a/packages/encoding/src/ascii.spec.ts b/packages/encoding/src/ascii.spec.ts
index a6942ec151..bae25b58b5 100644
--- a/packages/encoding/src/ascii.spec.ts
+++ b/packages/encoding/src/ascii.spec.ts
@@ -1,4 +1,4 @@
-import { fromAscii, toAscii } from "./ascii";
+import { fromAscii, toAscii } from "./ascii.ts";
 
 describe("ascii", () => {
   it("encodes to ascii", () => {
diff --git a/packages/encoding/src/base64.spec.ts b/packages/encoding/src/base64.spec.ts
index 46d6b7fa37..851d076d1d 100644
--- a/packages/encoding/src/base64.spec.ts
+++ b/packages/encoding/src/base64.spec.ts
@@ -1,4 +1,4 @@
-import { fromBase64, toBase64 } from "./base64";
+import { fromBase64, toBase64 } from "./base64.ts";
 
 describe("base64", () => {
   it("encodes to base64", () => {
diff --git a/packages/encoding/src/base64.ts b/packages/encoding/src/base64.ts
index ec9deac1e9..263f53fbeb 100644
--- a/packages/encoding/src/base64.ts
+++ b/packages/encoding/src/base64.ts
@@ -1,6 +1,6 @@
 import * as base64js from "base64-js";
 
-import { fixUint8Array } from "./uint8array";
+import { fixUint8Array } from "./uint8array.ts";
 
 export function toBase64(data: Uint8Array): string {
   return base64js.fromByteArray(data);
diff --git a/packages/encoding/src/bech32.spec.ts b/packages/encoding/src/bech32.spec.ts
index f0fef06984..12f0abf543 100644
--- a/packages/encoding/src/bech32.spec.ts
+++ b/packages/encoding/src/bech32.spec.ts
@@ -1,5 +1,5 @@
-import { fromBech32, normalizeBech32, toBech32 } from "./bech32";
-import { fromHex } from "./hex";
+import { fromBech32, normalizeBech32, toBech32 } from "./bech32.ts";
+import { fromHex } from "./hex.ts";
 
 describe("bech32", () => {
   // test data generate using https://github.com/nym-zone/bech32
diff --git a/packages/encoding/src/bech32.ts b/packages/encoding/src/bech32.ts
index ba4e2dfa32..2b2b30964d 100644
--- a/packages/encoding/src/bech32.ts
+++ b/packages/encoding/src/bech32.ts
@@ -1,6 +1,6 @@
 import { bech32 } from "@scure/base";
 
-import { fixUint8Array } from "./uint8array";
+import { fixUint8Array } from "./uint8array.ts";
 
 export function toBech32(prefix: string, data: Uint8Array, limit?: number): string {
   const address = bech32.encode(prefix, bech32.toWords(data), limit);
diff --git a/packages/encoding/src/hex.spec.ts b/packages/encoding/src/hex.spec.ts
index 7a7eed0c4b..312dcc5191 100644
--- a/packages/encoding/src/hex.spec.ts
+++ b/packages/encoding/src/hex.spec.ts
@@ -1,4 +1,4 @@
-import { fromHex, toHex } from "./hex";
+import { fromHex, toHex } from "./hex.ts";
 
 describe("fromHex", () => {
   it("works", () => {
diff --git a/packages/encoding/src/index.ts b/packages/encoding/src/index.ts
index e3f862a298..656c6d180e 100644
--- a/packages/encoding/src/index.ts
+++ b/packages/encoding/src/index.ts
@@ -1,7 +1,7 @@
-export { fromAscii, toAscii } from "./ascii";
-export { fromBase64, toBase64 } from "./base64";
-export { fromBech32, normalizeBech32, toBech32 } from "./bech32";
-export { fromHex, toHex } from "./hex";
-export { fromRfc3339, toRfc3339 } from "./rfc3339";
-export { fixUint8Array } from "./uint8array";
-export { fromUtf8, toUtf8 } from "./utf8";
+export { fromAscii, toAscii } from "./ascii.ts";
+export { fromBase64, toBase64 } from "./base64.ts";
+export { fromBech32, normalizeBech32, toBech32 } from "./bech32.ts";
+export { fromHex, toHex } from "./hex.ts";
+export { fromRfc3339, toRfc3339 } from "./rfc3339.ts";
+export { fixUint8Array } from "./uint8array.ts";
+export { fromUtf8, toUtf8 } from "./utf8.ts";
diff --git a/packages/encoding/src/rfc3339.spec.ts b/packages/encoding/src/rfc3339.spec.ts
index bb95dd48a5..35b498186c 100644
--- a/packages/encoding/src/rfc3339.spec.ts
+++ b/packages/encoding/src/rfc3339.spec.ts
@@ -1,4 +1,4 @@
-import { fromRfc3339, toRfc3339 } from "./rfc3339";
+import { fromRfc3339, toRfc3339 } from "./rfc3339.ts";
 
 describe("RFC3339", () => {
   it("parses dates with different time zones", () => {
diff --git a/packages/encoding/src/uint8array.spec.ts b/packages/encoding/src/uint8array.spec.ts
index 7428322c43..4b420d9c10 100644
--- a/packages/encoding/src/uint8array.spec.ts
+++ b/packages/encoding/src/uint8array.spec.ts
@@ -1,4 +1,4 @@
-import { fixUint8Array } from "./uint8array";
+import { fixUint8Array } from "./uint8array.ts";
 
 // Turned off in Chrome without secure context
 const hasSharedArrayBuffer = typeof SharedArrayBuffer !== "undefined";
diff --git a/packages/encoding/src/utf8.spec.ts b/packages/encoding/src/utf8.spec.ts
index 2f7af8bca6..a2dd1ef291 100644
--- a/packages/encoding/src/utf8.spec.ts
+++ b/packages/encoding/src/utf8.spec.ts
@@ -1,5 +1,5 @@
-import { toAscii } from "./ascii";
-import { fromUtf8, toUtf8 } from "./utf8";
+import { toAscii } from "./ascii.ts";
+import { fromUtf8, toUtf8 } from "./utf8.ts";
 
 describe("utf8", () => {
   it("encodes ascii strings", () => {
diff --git a/packages/encoding/src/utf8.ts b/packages/encoding/src/utf8.ts
index ca435dc977..d77a18e5a1 100644
--- a/packages/encoding/src/utf8.ts
+++ b/packages/encoding/src/utf8.ts
@@ -1,4 +1,4 @@
-import { fixUint8Array } from "./uint8array";
+import { fixUint8Array } from "./uint8array.ts";
 
 export function toUtf8(str: string): Uint8Array<ArrayBuffer> {
   return fixUint8Array(new TextEncoder().encode(str));
diff --git a/packages/faucet-client/src/faucetclient.spec.ts b/packages/faucet-client/src/faucetclient.spec.ts
index 9e83f99f7b..392bd4c5f6 100644
--- a/packages/faucet-client/src/faucetclient.spec.ts
+++ b/packages/faucet-client/src/faucetclient.spec.ts
@@ -1,4 +1,4 @@
-import { FaucetClient } from "./faucetclient";
+import { FaucetClient } from "./faucetclient.ts";
 
 const enabled = !!globalThis.process?.env.FAUCET_ENABLED;
 
diff --git a/packages/faucet-client/src/index.ts b/packages/faucet-client/src/index.ts
index 7a2633a5ba..df59cc096c 100644
--- a/packages/faucet-client/src/index.ts
+++ b/packages/faucet-client/src/index.ts
@@ -1 +1 @@
-export { FaucetClient } from "./faucetclient";
+export { FaucetClient } from "./faucetclient.ts";
diff --git a/packages/faucet/src/actions/generate.ts b/packages/faucet/src/actions/generate.ts
index 5f90494d96..ec8ad9b11a 100644
--- a/packages/faucet/src/actions/generate.ts
+++ b/packages/faucet/src/actions/generate.ts
@@ -1,8 +1,8 @@
 import { Bip39, Random } from "@cosmjs/crypto";
 
-import * as constants from "../constants";
-import { makePathBuilder } from "../pathbuilder";
-import { createWallets } from "../profile";
+import * as constants from "../constants.ts";
+import { makePathBuilder } from "../pathbuilder.ts";
+import { createWallets } from "../profile.ts";
 
 export async function generate(args: readonly string[]): Promise<void> {
   if (args.length > 0) {
diff --git a/packages/faucet/src/actions/help.ts b/packages/faucet/src/actions/help.ts
index 594149b066..dc583f60ae 100644
--- a/packages/faucet/src/actions/help.ts
+++ b/packages/faucet/src/actions/help.ts
@@ -1,4 +1,4 @@
-import { binaryName } from "../constants";
+import { binaryName } from "../constants.ts";
 
 export function help(): void {
   const out = `
diff --git a/packages/faucet/src/actions/index.ts b/packages/faucet/src/actions/index.ts
index 036bb34846..99dec3c6d0 100644
--- a/packages/faucet/src/actions/index.ts
+++ b/packages/faucet/src/actions/index.ts
@@ -1,4 +1,4 @@
-export { generate } from "./generate";
-export { help } from "./help";
-export { start } from "./start";
-export { version } from "./version";
+export { generate } from "./generate.ts";
+export { help } from "./help.ts";
+export { start } from "./start.ts";
+export { version } from "./version.ts";
diff --git a/packages/faucet/src/actions/start.ts b/packages/faucet/src/actions/start.ts
index 5890233c4b..b2ebb580ad 100644
--- a/packages/faucet/src/actions/start.ts
+++ b/packages/faucet/src/actions/start.ts
@@ -1,10 +1,10 @@
 import { StargateClient } from "@cosmjs/stargate";
 
-import { Webserver } from "../api/webserver";
-import * as constants from "../constants";
-import { logAccountsState } from "../debugging";
-import { Faucet } from "../faucet";
-import { makePathBuilder } from "../pathbuilder";
+import { Webserver } from "../api/webserver.ts";
+import * as constants from "../constants.ts";
+import { logAccountsState } from "../debugging.ts";
+import { Faucet } from "../faucet.ts";
+import { makePathBuilder } from "../pathbuilder.ts";
 
 export async function start(args: readonly string[]): Promise<void> {
   if (args.length < 1) {
diff --git a/packages/faucet/src/addresses.spec.ts b/packages/faucet/src/addresses.spec.ts
index f8020c665a..53e2580a94 100644
--- a/packages/faucet/src/addresses.spec.ts
+++ b/packages/faucet/src/addresses.spec.ts
@@ -1,4 +1,4 @@
-import { isValidAddress } from "./addresses";
+import { isValidAddress } from "./addresses.ts";
 
 describe("isValidAddress", () => {
   it("accepts account address", () => {
diff --git a/packages/faucet/src/api/httperror.spec.ts b/packages/faucet/src/api/httperror.spec.ts
index 0bb5811645..8b85f84aab 100644
--- a/packages/faucet/src/api/httperror.spec.ts
+++ b/packages/faucet/src/api/httperror.spec.ts
@@ -1,4 +1,4 @@
-import { HttpError } from "./httperror";
+import { HttpError } from "./httperror.ts";
 
 describe("HttpError", () => {
   it("can be constructed", () => {
diff --git a/packages/faucet/src/api/requestparser.spec.ts b/packages/faucet/src/api/requestparser.spec.ts
index c8ae110c92..f276026ac5 100644
--- a/packages/faucet/src/api/requestparser.spec.ts
+++ b/packages/faucet/src/api/requestparser.spec.ts
@@ -1,4 +1,4 @@
-import { RequestParser } from "./requestparser";
+import { RequestParser } from "./requestparser.ts";
 
 describe("RequestParser", () => {
   it("can process valid credit request with denom", () => {
diff --git a/packages/faucet/src/api/requestparser.ts b/packages/faucet/src/api/requestparser.ts
index 2ff99d3c9d..5bf359a79d 100644
--- a/packages/faucet/src/api/requestparser.ts
+++ b/packages/faucet/src/api/requestparser.ts
@@ -1,6 +1,6 @@
 import { isNonNullObject } from "@cosmjs/utils";
 
-import { HttpError } from "./httperror";
+import { HttpError } from "./httperror.ts";
 
 export interface CreditRequestBodyData {
   /** The base denomination */
diff --git a/packages/faucet/src/api/webserver.spec.ts b/packages/faucet/src/api/webserver.spec.ts
index 420e759255..318226508b 100644
--- a/packages/faucet/src/api/webserver.spec.ts
+++ b/packages/faucet/src/api/webserver.spec.ts
@@ -1,10 +1,10 @@
 import { makeCosmoshubPath } from "@cosmjs/stargate";
 import { sleep } from "@cosmjs/utils";
 
-import { Faucet } from "../faucet";
-import { simappEnabled } from "../testutils";
-import { TokenConfiguration } from "../tokenmanager";
-import { ChainConstants, Webserver } from "./webserver";
+import { Faucet } from "../faucet.ts";
+import { simappEnabled } from "../testutils.ts";
+import { TokenConfiguration } from "../tokenmanager.ts";
+import { ChainConstants, Webserver } from "./webserver.ts";
 
 const defaultTokenConfig: TokenConfiguration = {
   bankTokens: ["ucosm", "ustake"],
diff --git a/packages/faucet/src/api/webserver.ts b/packages/faucet/src/api/webserver.ts
index 53845f8888..41e5e3b5e5 100644
--- a/packages/faucet/src/api/webserver.ts
+++ b/packages/faucet/src/api/webserver.ts
@@ -3,11 +3,11 @@ import cors from "@koa/cors";
 // eslint-disable-next-line @typescript-eslint/naming-convention
 import Koa from "koa";
 
-import { isValidAddress } from "../addresses";
-import * as constants from "../constants";
-import { Faucet } from "../faucet";
-import { HttpError } from "./httperror";
-import { RequestParser } from "./requestparser";
+import { isValidAddress } from "../addresses.ts";
+import * as constants from "../constants.ts";
+import { Faucet } from "../faucet.ts";
+import { HttpError } from "./httperror.ts";
+import { RequestParser } from "./requestparser.ts";
 
 /** This will be passed 1:1 to the user */
 export interface ChainConstants {
diff --git a/packages/faucet/src/cli.ts b/packages/faucet/src/cli.ts
index a8d108cd18..f6d1c09e18 100644
--- a/packages/faucet/src/cli.ts
+++ b/packages/faucet/src/cli.ts
@@ -1,4 +1,4 @@
-import { generate, help, start, version } from "./actions";
+import { generate, help, start, version } from "./actions/index.ts";
 
 export function main(args: readonly string[]): void {
   if (args.length < 1) {
diff --git a/packages/faucet/src/constants.ts b/packages/faucet/src/constants.ts
index 7cdc16803b..5341958858 100644
--- a/packages/faucet/src/constants.ts
+++ b/packages/faucet/src/constants.ts
@@ -1,7 +1,7 @@
 import { GasPrice } from "@cosmjs/stargate";
 
-import { TokenConfiguration } from "./tokenmanager";
-import { parseBankTokens } from "./tokens";
+import { TokenConfiguration } from "./tokenmanager.ts";
+import { parseBankTokens } from "./tokens.ts";
 
 export const binaryName = "cosmos-faucet";
 export const memo: string | undefined = process.env.FAUCET_MEMO;
diff --git a/packages/faucet/src/debugging.ts b/packages/faucet/src/debugging.ts
index bad1055274..3a3ae357ae 100644
--- a/packages/faucet/src/debugging.ts
+++ b/packages/faucet/src/debugging.ts
@@ -1,6 +1,6 @@
 import { Coin } from "@cosmjs/stargate";
 
-import { MinimalAccount, SendJob } from "./types";
+import { MinimalAccount, SendJob } from "./types.ts";
 
 /** A string representation of a coin in a human-readable format that can change at any time */
 function debugCoin(coin: Coin): string {
diff --git a/packages/faucet/src/faucet.spec.ts b/packages/faucet/src/faucet.spec.ts
index f9c8cdc286..1a25dff31c 100644
--- a/packages/faucet/src/faucet.spec.ts
+++ b/packages/faucet/src/faucet.spec.ts
@@ -3,9 +3,9 @@ import { toBech32 } from "@cosmjs/encoding";
 import { makeCosmoshubPath, StargateClient } from "@cosmjs/stargate";
 import { assert } from "@cosmjs/utils";
 
-import { Faucet } from "./faucet";
-import { simappEnabled } from "./testutils";
-import { TokenConfiguration } from "./tokenmanager";
+import { Faucet } from "./faucet.ts";
+import { simappEnabled } from "./testutils.ts";
+import { TokenConfiguration } from "./tokenmanager.ts";
 
 const defaultTokenConfig: TokenConfiguration = {
   bankTokens: ["ucosm", "ustake"],
diff --git a/packages/faucet/src/faucet.ts b/packages/faucet/src/faucet.ts
index 40c367f8b7..00ac394df8 100644
--- a/packages/faucet/src/faucet.ts
+++ b/packages/faucet/src/faucet.ts
@@ -6,12 +6,12 @@ import {
 } from "@cosmjs/stargate";
 import { isDefined, sleep } from "@cosmjs/utils";
 
-import * as constants from "./constants";
-import { debugAccount, logAccountsState, logSendJob } from "./debugging";
-import { PathBuilder } from "./pathbuilder";
-import { createClients, createWallets } from "./profile";
-import { TokenConfiguration, TokenManager } from "./tokenmanager";
-import { MinimalAccount, SendJob } from "./types";
+import * as constants from "./constants.ts";
+import { debugAccount, logAccountsState, logSendJob } from "./debugging.ts";
+import { PathBuilder } from "./pathbuilder.ts";
+import { createClients, createWallets } from "./profile.ts";
+import { TokenConfiguration, TokenManager } from "./tokenmanager.ts";
+import { MinimalAccount, SendJob } from "./types.ts";
 
 export class Faucet {
   public static async make(
diff --git a/packages/faucet/src/pathbuilder.spec.ts b/packages/faucet/src/pathbuilder.spec.ts
index f48ee97189..e5759d6486 100644
--- a/packages/faucet/src/pathbuilder.spec.ts
+++ b/packages/faucet/src/pathbuilder.spec.ts
@@ -1,7 +1,7 @@
 import { Slip10RawIndex } from "@cosmjs/crypto";
 import { makeCosmoshubPath } from "@cosmjs/proto-signing";
 
-import { makePathBuilder, PathBuilder } from "./pathbuilder";
+import { makePathBuilder, PathBuilder } from "./pathbuilder.ts";
 
 describe("pathbuilder", () => {
   describe("PathBuilder", () => {
diff --git a/packages/faucet/src/profile.ts b/packages/faucet/src/profile.ts
index a29eb25432..b6616a44a2 100644
--- a/packages/faucet/src/profile.ts
+++ b/packages/faucet/src/profile.ts
@@ -2,7 +2,7 @@ import { pathToString } from "@cosmjs/crypto";
 import { DirectSecp256k1HdWallet, OfflineSigner } from "@cosmjs/proto-signing";
 import { SigningStargateClient } from "@cosmjs/stargate";
 
-import { PathBuilder } from "./pathbuilder";
+import { PathBuilder } from "./pathbuilder.ts";
 
 export async function createWallets(
   mnemonic: string,
diff --git a/packages/faucet/src/tokenmanager.spec.ts b/packages/faucet/src/tokenmanager.spec.ts
index dbdcb65028..c93db932cb 100644
--- a/packages/faucet/src/tokenmanager.spec.ts
+++ b/packages/faucet/src/tokenmanager.spec.ts
@@ -1,5 +1,5 @@
-import { TokenConfiguration, TokenManager } from "./tokenmanager";
-import { MinimalAccount } from "./types";
+import { TokenConfiguration, TokenManager } from "./tokenmanager.ts";
+import { MinimalAccount } from "./types.ts";
 
 const dummyConfig: TokenConfiguration = {
   bankTokens: ["utokenz", "mtrash"],
diff --git a/packages/faucet/src/tokenmanager.ts b/packages/faucet/src/tokenmanager.ts
index e0f283bbe2..c79bccff68 100644
--- a/packages/faucet/src/tokenmanager.ts
+++ b/packages/faucet/src/tokenmanager.ts
@@ -1,7 +1,7 @@
 import { Decimal, Uint53 } from "@cosmjs/math";
 import { Coin } from "@cosmjs/stargate";
 
-import { MinimalAccount } from "./types";
+import { MinimalAccount } from "./types.ts";
 
 const defaultCreditAmount = 10_000_000;
 
diff --git a/packages/faucet/src/tokens.spec.ts b/packages/faucet/src/tokens.spec.ts
index d2b1421cc8..d3ead53958 100644
--- a/packages/faucet/src/tokens.spec.ts
+++ b/packages/faucet/src/tokens.spec.ts
@@ -1,4 +1,4 @@
-import { parseBankToken, parseBankTokens } from "./tokens";
+import { parseBankToken, parseBankTokens } from "./tokens.ts";
 
 describe("tokens", () => {
   describe("parseBankToken", () => {
diff --git a/packages/json-rpc/src/compatibility.spec.ts b/packages/json-rpc/src/compatibility.spec.ts
index 485fc784c0..bc35c43208 100644
--- a/packages/json-rpc/src/compatibility.spec.ts
+++ b/packages/json-rpc/src/compatibility.spec.ts
@@ -1,4 +1,4 @@
-import { isJsonCompatibleArray, isJsonCompatibleDictionary, isJsonCompatibleValue } from "./compatibility";
+import { isJsonCompatibleArray, isJsonCompatibleDictionary, isJsonCompatibleValue } from "./compatibility.ts";
 
 describe("json", () => {
   function sum(a: number, b: number): number {
diff --git a/packages/json-rpc/src/id.spec.ts b/packages/json-rpc/src/id.spec.ts
index 7f5b51fb76..a742bb8019 100644
--- a/packages/json-rpc/src/id.spec.ts
+++ b/packages/json-rpc/src/id.spec.ts
@@ -1,4 +1,4 @@
-import { makeJsonRpcId } from "./id";
+import { makeJsonRpcId } from "./id.ts";
 
 describe("id", () => {
   describe("makeJsonRpcId", () => {
diff --git a/packages/json-rpc/src/index.ts b/packages/json-rpc/src/index.ts
index ee191537a7..1af462b947 100644
--- a/packages/json-rpc/src/index.ts
+++ b/packages/json-rpc/src/index.ts
@@ -1,12 +1,12 @@
-export { makeJsonRpcId } from "./id";
-export { type SimpleMessagingConnection, JsonRpcClient } from "./jsonrpcclient";
+export { makeJsonRpcId } from "./id.ts";
+export { type SimpleMessagingConnection, JsonRpcClient } from "./jsonrpcclient.ts";
 export {
   parseJsonRpcErrorResponse,
   parseJsonRpcId,
   parseJsonRpcRequest,
   parseJsonRpcResponse,
   parseJsonRpcSuccessResponse,
-} from "./parse";
+} from "./parse.ts";
 export type {
   JsonRpcError,
   JsonRpcErrorResponse,
@@ -14,5 +14,5 @@ export type {
   JsonRpcRequest,
   JsonRpcResponse,
   JsonRpcSuccessResponse,
-} from "./types";
-export { isJsonRpcErrorResponse, isJsonRpcSuccessResponse, jsonRpcCode } from "./types";
+} from "./types.ts";
+export { isJsonRpcErrorResponse, isJsonRpcSuccessResponse, jsonRpcCode } from "./types.ts";
diff --git a/packages/json-rpc/src/jsonrpcclient.spec.ts b/packages/json-rpc/src/jsonrpcclient.spec.ts
index d4baad6d22..3c2fb319cc 100644
--- a/packages/json-rpc/src/jsonrpcclient.spec.ts
+++ b/packages/json-rpc/src/jsonrpcclient.spec.ts
@@ -2,9 +2,9 @@
 
 import { Producer, Stream } from "xstream";
 
-import { JsonRpcClient, SimpleMessagingConnection } from "./jsonrpcclient";
-import { parseJsonRpcResponse } from "./parse";
-import { JsonRpcRequest, JsonRpcResponse } from "./types";
+import { JsonRpcClient, SimpleMessagingConnection } from "./jsonrpcclient.ts";
+import { parseJsonRpcResponse } from "./parse.ts";
+import { JsonRpcRequest, JsonRpcResponse } from "./types.ts";
 
 function makeSimpleMessagingConnection(
   worker: Worker,
diff --git a/packages/json-rpc/src/jsonrpcclient.ts b/packages/json-rpc/src/jsonrpcclient.ts
index 305491541f..d71f01cc9a 100644
--- a/packages/json-rpc/src/jsonrpcclient.ts
+++ b/packages/json-rpc/src/jsonrpcclient.ts
@@ -1,7 +1,7 @@
 import { firstEvent } from "@cosmjs/stream";
 import { Stream } from "xstream";
 
-import { isJsonRpcErrorResponse, JsonRpcRequest, JsonRpcResponse, JsonRpcSuccessResponse } from "./types";
+import { isJsonRpcErrorResponse, JsonRpcRequest, JsonRpcResponse, JsonRpcSuccessResponse } from "./types.ts";
 
 export interface SimpleMessagingConnection<Request, Response> {
   readonly responseStream: Stream<Response>;
diff --git a/packages/json-rpc/src/parse.spec.ts b/packages/json-rpc/src/parse.spec.ts
index cb8416de37..432b9218b3 100644
--- a/packages/json-rpc/src/parse.spec.ts
+++ b/packages/json-rpc/src/parse.spec.ts
@@ -3,8 +3,8 @@ import {
   parseJsonRpcId,
   parseJsonRpcResponse,
   parseJsonRpcSuccessResponse,
-} from "./parse";
-import { jsonRpcCode, JsonRpcErrorResponse, JsonRpcRequest, JsonRpcSuccessResponse } from "./types";
+} from "./parse.ts";
+import { jsonRpcCode, JsonRpcErrorResponse, JsonRpcRequest, JsonRpcSuccessResponse } from "./types.ts";
 
 describe("parse", () => {
   describe("parseJsonRpcId", () => {
diff --git a/packages/json-rpc/src/parse.ts b/packages/json-rpc/src/parse.ts
index ad30b1f90e..97881499ad 100644
--- a/packages/json-rpc/src/parse.ts
+++ b/packages/json-rpc/src/parse.ts
@@ -4,7 +4,7 @@ import {
   isJsonCompatibleValue,
   JsonCompatibleDictionary,
   JsonCompatibleValue,
-} from "./compatibility";
+} from "./compatibility.ts";
 import {
   JsonRpcError,
   JsonRpcErrorResponse,
@@ -12,7 +12,7 @@ import {
   JsonRpcRequest,
   JsonRpcResponse,
   JsonRpcSuccessResponse,
-} from "./types";
+} from "./types.ts";
 
 /**
  * Extracts ID field from request or response object.
diff --git a/packages/json-rpc/src/types.ts b/packages/json-rpc/src/types.ts
index edcfcdcbef..72938f8d18 100644
--- a/packages/json-rpc/src/types.ts
+++ b/packages/json-rpc/src/types.ts
@@ -1,4 +1,4 @@
-import { JsonCompatibleArray, JsonCompatibleDictionary, JsonCompatibleValue } from "./compatibility";
+import { JsonCompatibleArray, JsonCompatibleDictionary, JsonCompatibleValue } from "./compatibility.ts";
 
 export type JsonRpcId = number | string;
 
diff --git a/packages/json-rpc/src/workers/dummyservice.worker.ts b/packages/json-rpc/src/workers/dummyservice.worker.ts
index 2c7bc9bca4..ab1878c6ba 100644
--- a/packages/json-rpc/src/workers/dummyservice.worker.ts
+++ b/packages/json-rpc/src/workers/dummyservice.worker.ts
@@ -2,15 +2,15 @@
 
 // for testing only
 
-import { isJsonCompatibleDictionary } from "../compatibility";
-import { parseJsonRpcId, parseJsonRpcRequest } from "../parse";
+import { isJsonCompatibleDictionary } from "../compatibility.ts";
+import { parseJsonRpcId, parseJsonRpcRequest } from "../parse.ts";
 import {
   jsonRpcCode,
   JsonRpcErrorResponse,
   JsonRpcRequest,
   JsonRpcResponse,
   JsonRpcSuccessResponse,
-} from "../types";
+} from "../types.ts";
 
 function handleRequest(event: MessageEvent): JsonRpcResponse {
   let request: JsonRpcRequest;
diff --git a/packages/ledger-amino/src/demo/web.ts b/packages/ledger-amino/src/demo/web.ts
index 6178f692b4..1fbc4ebc7d 100644
--- a/packages/ledger-amino/src/demo/web.ts
+++ b/packages/ledger-amino/src/demo/web.ts
@@ -6,7 +6,7 @@ import { assert } from "@cosmjs/utils";
 // eslint-disable-next-line @typescript-eslint/naming-convention
 import TransportWebUSB from "@ledgerhq/hw-transport-webusb";
 
-import { LedgerSigner } from "../ledgersigner";
+import { LedgerSigner } from "../ledgersigner.ts";
 
 declare const window: any;
 declare const document: any;
diff --git a/packages/ledger-amino/src/index.ts b/packages/ledger-amino/src/index.ts
index f40e03398d..025f34d758 100644
--- a/packages/ledger-amino/src/index.ts
+++ b/packages/ledger-amino/src/index.ts
@@ -1,2 +1,2 @@
-export { type AddressAndPubkey, LedgerConnector } from "./ledgerconnector";
-export { LedgerSigner } from "./ledgersigner";
+export { type AddressAndPubkey, LedgerConnector } from "./ledgerconnector.ts";
+export { LedgerSigner } from "./ledgersigner.ts";
diff --git a/packages/ledger-amino/src/ledgersigner.spec.ts b/packages/ledger-amino/src/ledgersigner.spec.ts
index 8d2ac311ca..fefda95013 100644
--- a/packages/ledger-amino/src/ledgersigner.spec.ts
+++ b/packages/ledger-amino/src/ledgersigner.spec.ts
@@ -17,8 +17,8 @@ import {
 import { sleep } from "@cosmjs/utils";
 import Transport from "@ledgerhq/hw-transport";
 
-import { LedgerSigner } from "./ledgersigner";
-import { faucet, ledgerEnabled, simapp, simappEnabled } from "./testutils";
+import { LedgerSigner } from "./ledgersigner.ts";
+import { faucet, ledgerEnabled, simapp, simappEnabled } from "./testutils.ts";
 
 const interactiveTimeout = 120_000;
 
diff --git a/packages/ledger-amino/src/ledgersigner.ts b/packages/ledger-amino/src/ledgersigner.ts
index 6fdc2a3361..e83329bb31 100644
--- a/packages/ledger-amino/src/ledgersigner.ts
+++ b/packages/ledger-amino/src/ledgersigner.ts
@@ -11,7 +11,7 @@ import { HdPath } from "@cosmjs/crypto";
 // eslint-disable-next-line @typescript-eslint/naming-convention
 import Transport from "@ledgerhq/hw-transport";
 
-import { AddressAndPubkey, LedgerConnector, LedgerConnectorOptions } from "./ledgerconnector";
+import { AddressAndPubkey, LedgerConnector, LedgerConnectorOptions } from "./ledgerconnector.ts";
 
 export class LedgerSigner implements OfflineAminoSigner {
   private readonly connector: LedgerConnector;
diff --git a/packages/math/src/decimal.spec.ts b/packages/math/src/decimal.spec.ts
index dcefcad388..71c00417bc 100644
--- a/packages/math/src/decimal.spec.ts
+++ b/packages/math/src/decimal.spec.ts
@@ -1,5 +1,5 @@
-import { Decimal } from "./decimal";
-import { Uint32, Uint53, Uint64 } from "./integers";
+import { Decimal } from "./decimal.ts";
+import { Uint32, Uint53, Uint64 } from "./integers.ts";
 
 describe("Decimal", () => {
   describe("fromAtomics", () => {
diff --git a/packages/math/src/decimal.ts b/packages/math/src/decimal.ts
index 391fc44b8c..ddfd3b4708 100644
--- a/packages/math/src/decimal.ts
+++ b/packages/math/src/decimal.ts
@@ -1,4 +1,4 @@
-import { Uint32, Uint53, Uint64 } from "./integers";
+import { Uint32, Uint53, Uint64 } from "./integers.ts";
 
 // Too large values lead to massive memory usage. Limit to something sensible.
 // The largest value we need is 18 (Ether).
diff --git a/packages/math/src/index.ts b/packages/math/src/index.ts
index b888136fd9..5b8bed217a 100644
--- a/packages/math/src/index.ts
+++ b/packages/math/src/index.ts
@@ -1,2 +1,2 @@
-export { Decimal } from "./decimal";
-export { Int53, Uint32, Uint53, Uint64 } from "./integers";
+export { Decimal } from "./decimal.ts";
+export { Int53, Uint32, Uint53, Uint64 } from "./integers.ts";
diff --git a/packages/math/src/integers.spec.ts b/packages/math/src/integers.spec.ts
index c16972545a..bc1d654305 100644
--- a/packages/math/src/integers.spec.ts
+++ b/packages/math/src/integers.spec.ts
@@ -1,4 +1,4 @@
-import { Int53, Uint32, Uint53, Uint64 } from "./integers";
+import { Int53, Uint32, Uint53, Uint64 } from "./integers.ts";
 
 describe("Integers", () => {
   describe("Uint32", () => {
diff --git a/packages/proto-signing/src/decode.spec.ts b/packages/proto-signing/src/decode.spec.ts
index c0ceffc067..147c21e387 100644
--- a/packages/proto-signing/src/decode.spec.ts
+++ b/packages/proto-signing/src/decode.spec.ts
@@ -4,8 +4,8 @@ import { PubKey } from "cosmjs-types/cosmos/crypto/secp256k1/keys";
 import { SignMode } from "cosmjs-types/cosmos/tx/signing/v1beta1/signing";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { decodeTxRaw } from "./decode";
-import { faucet, testVectors } from "./testutils";
+import { decodeTxRaw } from "./decode.ts";
+import { faucet, testVectors } from "./testutils.ts";
 
 describe("decode", () => {
   describe("decodeTxRaw", () => {
diff --git a/packages/proto-signing/src/directsecp256k1hdwallet.spec.ts b/packages/proto-signing/src/directsecp256k1hdwallet.spec.ts
index 17c03cc744..2f83156dab 100644
--- a/packages/proto-signing/src/directsecp256k1hdwallet.spec.ts
+++ b/packages/proto-signing/src/directsecp256k1hdwallet.spec.ts
@@ -2,10 +2,10 @@ import { coins, makeCosmoshubPath } from "@cosmjs/amino";
 import { Secp256k1, Secp256k1Signature, sha256 } from "@cosmjs/crypto";
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { DirectSecp256k1HdWallet, extractKdfConfiguration } from "./directsecp256k1hdwallet";
-import { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing";
-import { base64Matcher, faucet, testVectors } from "./testutils";
-import { executeKdf, KdfConfiguration } from "./wallet";
+import { DirectSecp256k1HdWallet, extractKdfConfiguration } from "./directsecp256k1hdwallet.ts";
+import { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing.ts";
+import { base64Matcher, faucet, testVectors } from "./testutils.ts";
+import { executeKdf, KdfConfiguration } from "./wallet.ts";
 
 describe("DirectSecp256k1HdWallet", () => {
   // m/44'/118'/0'/0/0
diff --git a/packages/proto-signing/src/directsecp256k1hdwallet.ts b/packages/proto-signing/src/directsecp256k1hdwallet.ts
index 2b08633d27..aecc847f65 100644
--- a/packages/proto-signing/src/directsecp256k1hdwallet.ts
+++ b/packages/proto-signing/src/directsecp256k1hdwallet.ts
@@ -16,8 +16,8 @@ import { fromBase64, fromUtf8, toBase64, toBech32, toUtf8 } from "@cosmjs/encodi
 import { assert, isNonNullObject } from "@cosmjs/utils";
 import { SignDoc } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { AccountData, DirectSignResponse, OfflineDirectSigner } from "./signer";
-import { makeSignBytes } from "./signing";
+import { AccountData, DirectSignResponse, OfflineDirectSigner } from "./signer.ts";
+import { makeSignBytes } from "./signing.ts";
 import {
   decrypt,
   encrypt,
@@ -25,7 +25,7 @@ import {
   executeKdf,
   KdfConfiguration,
   supportedAlgorithms,
-} from "./wallet";
+} from "./wallet.ts";
 
 interface AccountDataWithPrivkey extends AccountData {
   readonly privkey: Uint8Array;
diff --git a/packages/proto-signing/src/directsecp256k1wallet.spec.ts b/packages/proto-signing/src/directsecp256k1wallet.spec.ts
index b6236f4e08..188ccbf15f 100644
--- a/packages/proto-signing/src/directsecp256k1wallet.spec.ts
+++ b/packages/proto-signing/src/directsecp256k1wallet.spec.ts
@@ -2,9 +2,9 @@ import { coins } from "@cosmjs/amino";
 import { Secp256k1, Secp256k1Signature, sha256 } from "@cosmjs/crypto";
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { DirectSecp256k1Wallet } from "./directsecp256k1wallet";
-import { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing";
-import { testVectors } from "./testutils";
+import { DirectSecp256k1Wallet } from "./directsecp256k1wallet.ts";
+import { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing.ts";
+import { testVectors } from "./testutils.ts";
 
 describe("DirectSecp256k1Wallet", () => {
   const defaultPrivkey = fromHex("b8c462d2bb0c1a92edf44f735021f16c270f28ee2c3d1cb49943a5e70a3c763e");
diff --git a/packages/proto-signing/src/directsecp256k1wallet.ts b/packages/proto-signing/src/directsecp256k1wallet.ts
index cdbbe5281f..f9fffb7dbe 100644
--- a/packages/proto-signing/src/directsecp256k1wallet.ts
+++ b/packages/proto-signing/src/directsecp256k1wallet.ts
@@ -3,8 +3,8 @@ import { Secp256k1, sha256 } from "@cosmjs/crypto";
 import { toBech32 } from "@cosmjs/encoding";
 import { SignDoc } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { AccountData, DirectSignResponse, OfflineDirectSigner } from "./signer";
-import { makeSignBytes } from "./signing";
+import { AccountData, DirectSignResponse, OfflineDirectSigner } from "./signer.ts";
+import { makeSignBytes } from "./signing.ts";
 
 /**
  * A wallet that holds a single secp256k1 keypair.
diff --git a/packages/proto-signing/src/index.ts b/packages/proto-signing/src/index.ts
index 96121cc992..293a0175a9 100644
--- a/packages/proto-signing/src/index.ts
+++ b/packages/proto-signing/src/index.ts
@@ -1,13 +1,13 @@
 // This type happens to be shared between Amino and Direct sign modes
-export { type DecodedTxRaw, decodeTxRaw } from "./decode";
+export { type DecodedTxRaw, decodeTxRaw } from "./decode.ts";
 export {
   type DirectSecp256k1HdWalletOptions,
   DirectSecp256k1HdWallet,
   extractKdfConfiguration,
-} from "./directsecp256k1hdwallet";
-export { DirectSecp256k1Wallet } from "./directsecp256k1wallet";
-export { makeCosmoshubPath } from "./paths";
-export { anyToSinglePubkey, decodeOptionalPubkey, decodePubkey, encodePubkey } from "./pubkey";
+} from "./directsecp256k1hdwallet.ts";
+export { DirectSecp256k1Wallet } from "./directsecp256k1wallet.ts";
+export { makeCosmoshubPath } from "./paths.ts";
+export { anyToSinglePubkey, decodeOptionalPubkey, decodePubkey, encodePubkey } from "./pubkey.ts";
 export type {
   DecodeObject,
   EncodeObject,
@@ -15,12 +15,12 @@ export type {
   PbjsGeneratedType,
   TsProtoGeneratedType,
   TxBodyEncodeObject,
-} from "./registry";
-export { isPbjsGeneratedType, isTsProtoGeneratedType, isTxBodyEncodeObject, Registry } from "./registry";
-export type { AccountData, Algo, DirectSignResponse, OfflineDirectSigner, OfflineSigner } from "./signer";
-export { isOfflineDirectSigner } from "./signer";
-export { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing";
-export { type KdfConfiguration, executeKdf } from "./wallet";
+} from "./registry.ts";
+export { isPbjsGeneratedType, isTsProtoGeneratedType, isTxBodyEncodeObject, Registry } from "./registry.ts";
+export type { AccountData, Algo, DirectSignResponse, OfflineDirectSigner, OfflineSigner } from "./signer.ts";
+export { isOfflineDirectSigner } from "./signer.ts";
+export { makeAuthInfoBytes, makeSignBytes, makeSignDoc } from "./signing.ts";
+export { type KdfConfiguration, executeKdf } from "./wallet.ts";
 
 // re-exports
 export type { Coin } from "@cosmjs/amino";
diff --git a/packages/proto-signing/src/paths.spec.ts b/packages/proto-signing/src/paths.spec.ts
index 17fd85b6f8..6547465688 100644
--- a/packages/proto-signing/src/paths.spec.ts
+++ b/packages/proto-signing/src/paths.spec.ts
@@ -1,6 +1,6 @@
 import { Slip10RawIndex } from "@cosmjs/crypto";
 
-import { makeCosmoshubPath } from "./paths";
+import { makeCosmoshubPath } from "./paths.ts";
 
 describe("paths", () => {
   describe("makeCosmoshubPath", () => {
diff --git a/packages/proto-signing/src/pubkey.spec.ts b/packages/proto-signing/src/pubkey.spec.ts
index 8a4cab11ce..c26444005c 100644
--- a/packages/proto-signing/src/pubkey.spec.ts
+++ b/packages/proto-signing/src/pubkey.spec.ts
@@ -1,7 +1,7 @@
 import { fromBase64 } from "@cosmjs/encoding";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { decodePubkey, encodePubkey } from "./pubkey";
+import { decodePubkey, encodePubkey } from "./pubkey.ts";
 
 describe("pubkey", () => {
   const defaultPubkeyBase64 = "AtQaCqFnshaZQp6rIkvAPyzThvCvXSDO+9AzbxVErqJP";
diff --git a/packages/proto-signing/src/registry.spec.ts b/packages/proto-signing/src/registry.spec.ts
index 750be14598..f8574e805a 100644
--- a/packages/proto-signing/src/registry.spec.ts
+++ b/packages/proto-signing/src/registry.spec.ts
@@ -6,7 +6,7 @@ import { TxBody } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { Any } from "cosmjs-types/google/protobuf/any";
 import { Field, Type } from "protobufjs";
 
-import { isPbjsGeneratedType, isTsProtoGeneratedType, Registry } from "./registry";
+import { isPbjsGeneratedType, isTsProtoGeneratedType, Registry } from "./registry.ts";
 
 describe("registry demo", () => {
   it("works with a default msg", () => {
diff --git a/packages/proto-signing/src/signing.spec.ts b/packages/proto-signing/src/signing.spec.ts
index 7e8a6d7607..3d6611924c 100644
--- a/packages/proto-signing/src/signing.spec.ts
+++ b/packages/proto-signing/src/signing.spec.ts
@@ -3,11 +3,11 @@ import { PubKey } from "cosmjs-types/cosmos/crypto/secp256k1/keys";
 import { SignMode } from "cosmjs-types/cosmos/tx/signing/v1beta1/signing";
 import { TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { decodeTxRaw } from "./decode";
-import { DirectSecp256k1HdWallet } from "./directsecp256k1hdwallet";
-import { Registry } from "./registry";
-import { makeSignBytes, makeSignDoc } from "./signing";
-import { faucet, testVectors } from "./testutils";
+import { decodeTxRaw } from "./decode.ts";
+import { DirectSecp256k1HdWallet } from "./directsecp256k1hdwallet.ts";
+import { Registry } from "./registry.ts";
+import { makeSignBytes, makeSignDoc } from "./signing.ts";
+import { faucet, testVectors } from "./testutils.ts";
 
 describe("signing", () => {
   const chainId = "simd-testing";
diff --git a/packages/socket/src/index.ts b/packages/socket/src/index.ts
index a70ebe5185..3f6f6108f7 100644
--- a/packages/socket/src/index.ts
+++ b/packages/socket/src/index.ts
@@ -1,9 +1,9 @@
-export { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket";
-export { ReconnectingSocket } from "./reconnectingsocket";
+export { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket.ts";
+export { ReconnectingSocket } from "./reconnectingsocket.ts";
 export type {
   SocketWrapperCloseEvent,
   SocketWrapperErrorEvent,
   SocketWrapperMessageEvent,
-} from "./socketwrapper";
-export { SocketWrapper } from "./socketwrapper";
-export { StreamingSocket } from "./streamingsocket";
+} from "./socketwrapper.ts";
+export { SocketWrapper } from "./socketwrapper.ts";
+export { StreamingSocket } from "./streamingsocket.ts";
diff --git a/packages/socket/src/queueingstreamingsocket.spec.ts b/packages/socket/src/queueingstreamingsocket.spec.ts
index a17c21e5ab..45328c5970 100644
--- a/packages/socket/src/queueingstreamingsocket.spec.ts
+++ b/packages/socket/src/queueingstreamingsocket.spec.ts
@@ -1,4 +1,4 @@
-import { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket";
+import { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket.ts";
 
 const enabled = !!globalThis.process?.env.SOCKETSERVER_ENABLED;
 
diff --git a/packages/socket/src/queueingstreamingsocket.ts b/packages/socket/src/queueingstreamingsocket.ts
index c3af8c21a0..5ecbfb40d7 100644
--- a/packages/socket/src/queueingstreamingsocket.ts
+++ b/packages/socket/src/queueingstreamingsocket.ts
@@ -1,8 +1,8 @@
 import { DefaultValueProducer, ValueAndUpdates } from "@cosmjs/stream";
 import { Listener, Producer, Stream } from "xstream";
 
-import { SocketWrapperMessageEvent } from "./socketwrapper";
-import { StreamingSocket } from "./streamingsocket";
+import { SocketWrapperMessageEvent } from "./socketwrapper.ts";
+import { StreamingSocket } from "./streamingsocket.ts";
 
 export enum ConnectionStatus {
   Unconnected,
diff --git a/packages/socket/src/reconnectingsocket.spec.ts b/packages/socket/src/reconnectingsocket.spec.ts
index b2762716a2..20df4e0362 100644
--- a/packages/socket/src/reconnectingsocket.spec.ts
+++ b/packages/socket/src/reconnectingsocket.spec.ts
@@ -1,4 +1,4 @@
-import { ReconnectingSocket } from "./reconnectingsocket";
+import { ReconnectingSocket } from "./reconnectingsocket.ts";
 
 /** @see https://nodejs.org/api/child_process.html#child_process_child_process_exec_command_options_callback */
 type Exec = (command: string, callback: (error: null | (Error & { readonly code?: number })) => void) => void;
diff --git a/packages/socket/src/reconnectingsocket.ts b/packages/socket/src/reconnectingsocket.ts
index 84a306a4b4..42ebc1561f 100644
--- a/packages/socket/src/reconnectingsocket.ts
+++ b/packages/socket/src/reconnectingsocket.ts
@@ -1,8 +1,8 @@
 import { ValueAndUpdates } from "@cosmjs/stream";
 import { Listener, Producer, Stream } from "xstream";
 
-import { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket";
-import { SocketWrapperMessageEvent } from "./socketwrapper";
+import { ConnectionStatus, QueueingStreamingSocket } from "./queueingstreamingsocket.ts";
+import { SocketWrapperMessageEvent } from "./socketwrapper.ts";
 
 /**
  * A wrapper around QueueingStreamingSocket that reconnects automatically.
diff --git a/packages/socket/src/socketwrapper.spec.ts b/packages/socket/src/socketwrapper.spec.ts
index 2b53201a54..fa74c8a300 100644
--- a/packages/socket/src/socketwrapper.spec.ts
+++ b/packages/socket/src/socketwrapper.spec.ts
@@ -1,4 +1,4 @@
-import { SocketWrapper } from "./socketwrapper";
+import { SocketWrapper } from "./socketwrapper.ts";
 
 const enabled = !!globalThis.process?.env.SOCKETSERVER_ENABLED;
 
diff --git a/packages/socket/src/streamingsocket.spec.ts b/packages/socket/src/streamingsocket.spec.ts
index 4e55413009..db2f34e00a 100644
--- a/packages/socket/src/streamingsocket.spec.ts
+++ b/packages/socket/src/streamingsocket.spec.ts
@@ -1,6 +1,6 @@
 import { toListPromise } from "@cosmjs/stream";
 
-import { StreamingSocket } from "./streamingsocket";
+import { StreamingSocket } from "./streamingsocket.ts";
 
 const enabled = !!globalThis.process?.env.SOCKETSERVER_ENABLED;
 
diff --git a/packages/socket/src/streamingsocket.ts b/packages/socket/src/streamingsocket.ts
index a0e0805afe..2753a04de9 100644
--- a/packages/socket/src/streamingsocket.ts
+++ b/packages/socket/src/streamingsocket.ts
@@ -1,6 +1,6 @@
 import { Listener, Producer, Stream } from "xstream";
 
-import { SocketWrapper, SocketWrapperMessageEvent } from "./socketwrapper";
+import { SocketWrapper, SocketWrapperMessageEvent } from "./socketwrapper.ts";
 
 /**
  * A WebSocket wrapper that exposes all events as a stream.
diff --git a/packages/stargate/src/accounts.spec.ts b/packages/stargate/src/accounts.spec.ts
index 86088d3753..8cd2837c1f 100644
--- a/packages/stargate/src/accounts.spec.ts
+++ b/packages/stargate/src/accounts.spec.ts
@@ -1,7 +1,7 @@
 import { fromBase64 } from "@cosmjs/encoding";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { accountFromAny } from "./accounts";
+import { accountFromAny } from "./accounts.ts";
 
 describe("accounts", () => {
   describe("accountFromAny", () => {
diff --git a/packages/stargate/src/aminotypes.spec.ts b/packages/stargate/src/aminotypes.spec.ts
index ff7687065c..b93ac8119b 100644
--- a/packages/stargate/src/aminotypes.spec.ts
+++ b/packages/stargate/src/aminotypes.spec.ts
@@ -1,8 +1,8 @@
 import { coin } from "@cosmjs/proto-signing";
 import { MsgDelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { AminoTypes } from "./aminotypes";
-import { createBankAminoConverters, createStakingAminoConverters } from "./modules";
+import { AminoTypes } from "./aminotypes.ts";
+import { createBankAminoConverters, createStakingAminoConverters } from "./modules/index.ts";
 
 describe("AminoTypes", () => {
   describe("constructor", () => {
diff --git a/packages/stargate/src/fee.spec.ts b/packages/stargate/src/fee.spec.ts
index 9ba93e8a27..f32e9f6eee 100644
--- a/packages/stargate/src/fee.spec.ts
+++ b/packages/stargate/src/fee.spec.ts
@@ -1,6 +1,6 @@
 import { Decimal } from "@cosmjs/math";
 
-import { calculateFee, GasPrice } from "./fee";
+import { calculateFee, GasPrice } from "./fee.ts";
 
 describe("GasPrice", () => {
   it("can be constructed", () => {
diff --git a/packages/stargate/src/index.ts b/packages/stargate/src/index.ts
index 0f64e494ff..93e1ff4fc6 100644
--- a/packages/stargate/src/index.ts
+++ b/packages/stargate/src/index.ts
@@ -1,11 +1,11 @@
-export type { Account, AccountParser } from "./accounts";
-export { accountFromAny } from "./accounts";
-export type { AminoConverter, AminoConverters } from "./aminotypes";
-export { AminoTypes } from "./aminotypes";
-export type { Attribute, Event } from "./events";
-export { fromTendermintEvent } from "./events";
-export { calculateFee, GasPrice } from "./fee";
-export * as logs from "./logs";
+export type { Account, AccountParser } from "./accounts.ts";
+export { accountFromAny } from "./accounts.ts";
+export type { AminoConverter, AminoConverters } from "./aminotypes.ts";
+export { AminoTypes } from "./aminotypes.ts";
+export type { Attribute, Event } from "./events.ts";
+export { fromTendermintEvent } from "./events.ts";
+export { calculateFee, GasPrice } from "./fee.ts";
+export * as logs from "./logs.ts";
 export type {
   AminoMsgBeginRedelegate,
   AminoMsgCreateValidator,
@@ -51,7 +51,7 @@ export type {
   MsgWithdrawDelegatorRewardEncodeObject,
   StakingExtension,
   TxExtension,
-} from "./modules";
+} from "./modules/index.ts";
 export {
   createAuthzAminoConverters,
   createBankAminoConverters,
@@ -109,23 +109,23 @@ export {
   setupSlashingExtension,
   setupStakingExtension,
   setupTxExtension,
-} from "./modules";
-export { makeMultisignedTx, makeMultisignedTxBytes } from "./multisignature";
-export type { ProtobufRpcClient, QueryAbciResponse, QueryStoreResponse } from "./queryclient";
+} from "./modules/index.ts";
+export { makeMultisignedTx, makeMultisignedTxBytes } from "./multisignature.ts";
+export type { ProtobufRpcClient, QueryAbciResponse, QueryStoreResponse } from "./queryclient/index.ts";
 export {
   createPagination,
   createProtobufRpcClient,
   decodeCosmosSdkDecFromProto,
   QueryClient,
-} from "./queryclient";
-export type { SearchPair, SearchTxQuery } from "./search";
-export { isSearchTxQueryArray } from "./search";
-export type { SignerData, SigningStargateClientOptions } from "./signingstargateclient";
+} from "./queryclient/index.ts";
+export type { SearchPair, SearchTxQuery } from "./search.ts";
+export { isSearchTxQueryArray } from "./search.ts";
+export type { SignerData, SigningStargateClientOptions } from "./signingstargateclient.ts";
 export {
   createDefaultAminoConverters,
   defaultRegistryTypes,
   SigningStargateClient,
-} from "./signingstargateclient";
+} from "./signingstargateclient.ts";
 export type {
   Block,
   BlockHeader,
@@ -133,7 +133,7 @@ export type {
   IndexedTx,
   SequenceResponse,
   StargateClientOptions,
-} from "./stargateclient";
+} from "./stargateclient.ts";
 export {
   assertIsDeliverTxFailure,
   assertIsDeliverTxSuccess,
@@ -142,7 +142,7 @@ export {
   isDeliverTxSuccess,
   StargateClient,
   TimeoutError,
-} from "./stargateclient";
+} from "./stargateclient.ts";
 export type { StdFee } from "@cosmjs/amino";
 export type { Coin } from "@cosmjs/proto-signing";
 export { coin, coins, makeCosmoshubPath, parseCoins } from "@cosmjs/proto-signing";
diff --git a/packages/stargate/src/logs.ts b/packages/stargate/src/logs.ts
index 1e97d56031..2451aa396e 100644
--- a/packages/stargate/src/logs.ts
+++ b/packages/stargate/src/logs.ts
@@ -1,7 +1,7 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { isNonNullObject } from "@cosmjs/utils";
 
-import { Attribute, Event } from "./events";
+import { Attribute, Event } from "./events.ts";
 
 export interface Log {
   readonly msg_index: number;
diff --git a/packages/stargate/src/modules/auth/queries.spec.ts b/packages/stargate/src/modules/auth/queries.spec.ts
index 11aa7a6ae9..68f3da0db3 100644
--- a/packages/stargate/src/modules/auth/queries.spec.ts
+++ b/packages/stargate/src/modules/auth/queries.spec.ts
@@ -4,9 +4,9 @@ import { assert } from "@cosmjs/utils";
 import { BaseAccount } from "cosmjs-types/cosmos/auth/v1beta1/auth";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { QueryClient } from "../../queryclient";
-import { nonExistentAddress, simapp, simappEnabled, unused, validator } from "../../testutils";
-import { AuthExtension, setupAuthExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { nonExistentAddress, simapp, simappEnabled, unused, validator } from "../../testutils.ts";
+import { AuthExtension, setupAuthExtension } from "./queries.ts";
 
 async function makeClientWithAuth(rpcUrl: string): Promise<[QueryClient & AuthExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/auth/queries.ts b/packages/stargate/src/modules/auth/queries.ts
index 348f7d8f3d..572ea61882 100644
--- a/packages/stargate/src/modules/auth/queries.ts
+++ b/packages/stargate/src/modules/auth/queries.ts
@@ -1,7 +1,7 @@
 import { QueryClientImpl } from "cosmjs-types/cosmos/auth/v1beta1/query";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface AuthExtension {
   readonly auth: {
diff --git a/packages/stargate/src/modules/authz/aminomessages.ts b/packages/stargate/src/modules/authz/aminomessages.ts
index b485788434..bbf8e0099e 100644
--- a/packages/stargate/src/modules/authz/aminomessages.ts
+++ b/packages/stargate/src/modules/authz/aminomessages.ts
@@ -1,4 +1,4 @@
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 export function createAuthzAminoConverters(): AminoConverters {
   return {
diff --git a/packages/stargate/src/modules/authz/queries.spec.ts b/packages/stargate/src/modules/authz/queries.spec.ts
index 255fe0ab5c..fb383ee997 100644
--- a/packages/stargate/src/modules/authz/queries.spec.ts
+++ b/packages/stargate/src/modules/authz/queries.spec.ts
@@ -4,17 +4,17 @@ import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 import { assertDefined, sleep } from "@cosmjs/utils";
 import { GenericAuthorization } from "cosmjs-types/cosmos/authz/v1beta1/authz";
 
-import { QueryClient } from "../../queryclient";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
+import { QueryClient } from "../../queryclient/index.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
   makeRandomAddress,
   simapp,
   simappEnabled,
-} from "../../testutils";
-import { AuthzExtension, setupAuthzExtension } from "./queries";
+} from "../../testutils.ts";
+import { AuthzExtension, setupAuthzExtension } from "./queries.ts";
 
 async function makeClientWithAuthz(rpcUrl: string): Promise<[QueryClient & AuthzExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/authz/queries.ts b/packages/stargate/src/modules/authz/queries.ts
index 0dd2b53b6d..8bf913603a 100644
--- a/packages/stargate/src/modules/authz/queries.ts
+++ b/packages/stargate/src/modules/authz/queries.ts
@@ -5,7 +5,7 @@ import {
   QueryGrantsResponse,
 } from "cosmjs-types/cosmos/authz/v1beta1/query";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface AuthzExtension {
   readonly authz: {
diff --git a/packages/stargate/src/modules/bank/aminomessages.spec.ts b/packages/stargate/src/modules/bank/aminomessages.spec.ts
index aa37583a05..e20df3e511 100644
--- a/packages/stargate/src/modules/bank/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/bank/aminomessages.spec.ts
@@ -1,8 +1,8 @@
 import { coins } from "@cosmjs/proto-signing";
 import { MsgMultiSend, MsgSend } from "cosmjs-types/cosmos/bank/v1beta1/tx";
 
-import { AminoTypes } from "../../aminotypes";
-import { AminoMsgMultiSend, AminoMsgSend, createBankAminoConverters } from "./aminomessages";
+import { AminoTypes } from "../../aminotypes.ts";
+import { AminoMsgMultiSend, AminoMsgSend, createBankAminoConverters } from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("toAmino", () => {
diff --git a/packages/stargate/src/modules/bank/aminomessages.ts b/packages/stargate/src/modules/bank/aminomessages.ts
index dad7c02b67..7991bafbb0 100644
--- a/packages/stargate/src/modules/bank/aminomessages.ts
+++ b/packages/stargate/src/modules/bank/aminomessages.ts
@@ -2,7 +2,7 @@
 import { AminoMsg, Coin } from "@cosmjs/amino";
 import { MsgMultiSend, MsgSend } from "cosmjs-types/cosmos/bank/v1beta1/tx";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 /** A high level transaction of the coin module */
 export interface AminoMsgSend extends AminoMsg {
diff --git a/packages/stargate/src/modules/bank/queries.spec.ts b/packages/stargate/src/modules/bank/queries.spec.ts
index 54d48cc954..2cab9570b4 100644
--- a/packages/stargate/src/modules/bank/queries.spec.ts
+++ b/packages/stargate/src/modules/bank/queries.spec.ts
@@ -1,14 +1,14 @@
 import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 
-import { QueryClient } from "../../queryclient";
+import { QueryClient } from "../../queryclient/index.ts";
 import {
   nonExistentAddress,
   nonNegativeIntegerMatcher,
   simapp,
   simappEnabled,
   unused,
-} from "../../testutils";
-import { BankExtension, setupBankExtension } from "./queries";
+} from "../../testutils.ts";
+import { BankExtension, setupBankExtension } from "./queries.ts";
 
 async function makeClientWithBank(rpcUrl: string): Promise<[QueryClient & BankExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/bank/queries.ts b/packages/stargate/src/modules/bank/queries.ts
index 73d81c5bcc..8355f76bf7 100644
--- a/packages/stargate/src/modules/bank/queries.ts
+++ b/packages/stargate/src/modules/bank/queries.ts
@@ -8,7 +8,7 @@ import {
 } from "cosmjs-types/cosmos/bank/v1beta1/query";
 import { Coin } from "cosmjs-types/cosmos/base/v1beta1/coin";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface BankExtension {
   readonly bank: {
diff --git a/packages/stargate/src/modules/crisis/aminomessages.ts b/packages/stargate/src/modules/crisis/aminomessages.ts
index a8f4721de8..c6d88ece00 100644
--- a/packages/stargate/src/modules/crisis/aminomessages.ts
+++ b/packages/stargate/src/modules/crisis/aminomessages.ts
@@ -1,7 +1,7 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { AminoMsg } from "@cosmjs/amino";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 // See https://github.com/cosmos/cosmos-sdk/blob/v0.45.1/proto/cosmos/crisis/v1beta1/tx.proto
 
diff --git a/packages/stargate/src/modules/distribution/aminomessages.spec.ts b/packages/stargate/src/modules/distribution/aminomessages.spec.ts
index 3dbf625565..9f1e4ed59b 100644
--- a/packages/stargate/src/modules/distribution/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/distribution/aminomessages.spec.ts
@@ -6,14 +6,14 @@ import {
   MsgWithdrawValidatorCommission,
 } from "cosmjs-types/cosmos/distribution/v1beta1/tx";
 
-import { AminoTypes } from "../../aminotypes";
+import { AminoTypes } from "../../aminotypes.ts";
 import {
   AminoMsgFundCommunityPool,
   AminoMsgSetWithdrawAddress,
   AminoMsgWithdrawDelegatorReward,
   AminoMsgWithdrawValidatorCommission,
   createDistributionAminoConverters,
-} from "./aminomessages";
+} from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("toAmino", () => {
diff --git a/packages/stargate/src/modules/distribution/aminomessages.ts b/packages/stargate/src/modules/distribution/aminomessages.ts
index 12836d4e84..d3468ddf61 100644
--- a/packages/stargate/src/modules/distribution/aminomessages.ts
+++ b/packages/stargate/src/modules/distribution/aminomessages.ts
@@ -7,7 +7,7 @@ import {
   MsgWithdrawValidatorCommission,
 } from "cosmjs-types/cosmos/distribution/v1beta1/tx";
 
-import { AminoConverter } from "../..";
+import { AminoConverter } from "../../index.ts";
 
 /** Changes the withdraw address for a delegator (or validator self-delegation) */
 export interface AminoMsgSetWithdrawAddress extends AminoMsg {
diff --git a/packages/stargate/src/modules/distribution/queries.spec.ts b/packages/stargate/src/modules/distribution/queries.spec.ts
index 2465f6ef9d..18236a5bac 100644
--- a/packages/stargate/src/modules/distribution/queries.spec.ts
+++ b/packages/stargate/src/modules/distribution/queries.spec.ts
@@ -3,12 +3,12 @@ import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 import { sleep } from "@cosmjs/utils";
 import { MsgDelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { QueryClient } from "../../queryclient";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
-import { defaultSigningClientOptions, faucet, simapp, simappEnabled, validator } from "../../testutils";
-import { MsgDelegateEncodeObject } from "../";
-import { DistributionExtension, setupDistributionExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
+import { defaultSigningClientOptions, faucet, simapp, simappEnabled, validator } from "../../testutils.ts";
+import { MsgDelegateEncodeObject } from "../index.ts";
+import { DistributionExtension, setupDistributionExtension } from "./queries.ts";
 
 async function makeClientWithDistribution(
   rpcUrl: string,
diff --git a/packages/stargate/src/modules/distribution/queries.ts b/packages/stargate/src/modules/distribution/queries.ts
index f7c5cd096b..8cccc1b169 100644
--- a/packages/stargate/src/modules/distribution/queries.ts
+++ b/packages/stargate/src/modules/distribution/queries.ts
@@ -11,7 +11,7 @@ import {
   QueryValidatorSlashesResponse,
 } from "cosmjs-types/cosmos/distribution/v1beta1/query";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface DistributionExtension {
   readonly distribution: {
diff --git a/packages/stargate/src/modules/evidence/aminomessages.ts b/packages/stargate/src/modules/evidence/aminomessages.ts
index 2c94fcf971..322cbd394e 100644
--- a/packages/stargate/src/modules/evidence/aminomessages.ts
+++ b/packages/stargate/src/modules/evidence/aminomessages.ts
@@ -1,7 +1,7 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { AminoMsg } from "@cosmjs/amino";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 // See https://github.com/cosmos/cosmos-sdk/blob/v0.45.1/proto/cosmos/evidence/v1beta1/tx.proto
 
diff --git a/packages/stargate/src/modules/feegrant/aminomessages.ts b/packages/stargate/src/modules/feegrant/aminomessages.ts
index c36bc9a93d..208b0018da 100644
--- a/packages/stargate/src/modules/feegrant/aminomessages.ts
+++ b/packages/stargate/src/modules/feegrant/aminomessages.ts
@@ -1,4 +1,4 @@
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 export function createFeegrantAminoConverters(): AminoConverters {
   return {
diff --git a/packages/stargate/src/modules/feegrant/queries.ts b/packages/stargate/src/modules/feegrant/queries.ts
index f37634cf1a..4c4da1968b 100644
--- a/packages/stargate/src/modules/feegrant/queries.ts
+++ b/packages/stargate/src/modules/feegrant/queries.ts
@@ -4,7 +4,7 @@ import {
   QueryClientImpl,
 } from "cosmjs-types/cosmos/feegrant/v1beta1/query";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface FeegrantExtension {
   readonly feegrant: {
diff --git a/packages/stargate/src/modules/gov/aminomessages.spec.ts b/packages/stargate/src/modules/gov/aminomessages.spec.ts
index 7199e111b1..71fc919a76 100644
--- a/packages/stargate/src/modules/gov/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/gov/aminomessages.spec.ts
@@ -1,14 +1,14 @@
 import { TextProposal, VoteOption } from "cosmjs-types/cosmos/gov/v1beta1/gov";
 import { MsgDeposit, MsgSubmitProposal, MsgVote, MsgVoteWeighted } from "cosmjs-types/cosmos/gov/v1beta1/tx";
 
-import { AminoTypes } from "../../aminotypes";
+import { AminoTypes } from "../../aminotypes.ts";
 import {
   AminoMsgDeposit,
   AminoMsgSubmitProposal,
   AminoMsgVote,
   AminoMsgVoteWeighted,
   createGovAminoConverters,
-} from "./aminomessages";
+} from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("toAmino", () => {
diff --git a/packages/stargate/src/modules/gov/aminomessages.ts b/packages/stargate/src/modules/gov/aminomessages.ts
index 37aeee3c23..6a9617a5e6 100644
--- a/packages/stargate/src/modules/gov/aminomessages.ts
+++ b/packages/stargate/src/modules/gov/aminomessages.ts
@@ -6,8 +6,8 @@ import { TextProposal, voteOptionFromJSON } from "cosmjs-types/cosmos/gov/v1beta
 import { MsgDeposit, MsgSubmitProposal, MsgVote, MsgVoteWeighted } from "cosmjs-types/cosmos/gov/v1beta1/tx";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { AminoConverters } from "../../aminotypes";
-import { decodeCosmosSdkDecFromProto } from "../../queryclient";
+import { AminoConverters } from "../../aminotypes.ts";
+import { decodeCosmosSdkDecFromProto } from "../../queryclient/index.ts";
 
 /** Supports submitting arbitrary proposal content. */
 export interface AminoMsgSubmitProposal extends AminoMsg {
diff --git a/packages/stargate/src/modules/gov/messages.spec.ts b/packages/stargate/src/modules/gov/messages.spec.ts
index ded23bdb12..7828ff513e 100644
--- a/packages/stargate/src/modules/gov/messages.spec.ts
+++ b/packages/stargate/src/modules/gov/messages.spec.ts
@@ -4,9 +4,9 @@ import { assert, sleep } from "@cosmjs/utils";
 import { TextProposal, VoteOption } from "cosmjs-types/cosmos/gov/v1beta1/gov";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { longify } from "../../queryclient";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
+import { longify } from "../../queryclient/index.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
@@ -15,9 +15,9 @@ import {
   simapp50Enabled,
   simappEnabled,
   validator,
-} from "../../testutils";
-import { MsgDelegateEncodeObject, MsgSubmitProposalEncodeObject, MsgVoteEncodeObject } from "../";
-import { MsgVoteWeightedEncodeObject } from "./messages";
+} from "../../testutils.ts";
+import { MsgDelegateEncodeObject, MsgSubmitProposalEncodeObject, MsgVoteEncodeObject } from "../index.ts";
+import { MsgVoteWeightedEncodeObject } from "./messages.ts";
 
 (simappEnabled ? describe : xdescribe)("gov messages", () => {
   const defaultFee = {
diff --git a/packages/stargate/src/modules/gov/queries.spec.ts b/packages/stargate/src/modules/gov/queries.spec.ts
index 558f270c07..f9a014a942 100644
--- a/packages/stargate/src/modules/gov/queries.spec.ts
+++ b/packages/stargate/src/modules/gov/queries.spec.ts
@@ -12,9 +12,9 @@ import {
 } from "cosmjs-types/cosmos/gov/v1beta1/gov";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { longify, QueryClient } from "../../queryclient";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
+import { longify, QueryClient } from "../../queryclient/index.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
@@ -22,9 +22,9 @@ import {
   simapp,
   simappEnabled,
   validator,
-} from "../../testutils";
-import { MsgDelegateEncodeObject, MsgSubmitProposalEncodeObject, MsgVoteEncodeObject } from "../";
-import { GovExtension, setupGovExtension } from "./queries";
+} from "../../testutils.ts";
+import { MsgDelegateEncodeObject, MsgSubmitProposalEncodeObject, MsgVoteEncodeObject } from "../index.ts";
+import { GovExtension, setupGovExtension } from "./queries.ts";
 
 async function makeClientWithGov(rpcUrl: string): Promise<[QueryClient & GovExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/gov/queries.ts b/packages/stargate/src/modules/gov/queries.ts
index 688baaedbf..e69f816d2c 100644
--- a/packages/stargate/src/modules/gov/queries.ts
+++ b/packages/stargate/src/modules/gov/queries.ts
@@ -12,7 +12,7 @@ import {
   QueryVotesResponse,
 } from "cosmjs-types/cosmos/gov/v1beta1/query";
 
-import { createPagination, createProtobufRpcClient, longify, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, longify, QueryClient } from "../../queryclient/index.ts";
 
 export type GovParamsType = "deposit" | "tallying" | "voting";
 
diff --git a/packages/stargate/src/modules/group/aminomessages.ts b/packages/stargate/src/modules/group/aminomessages.ts
index 95cd8ba667..d6d8228d06 100644
--- a/packages/stargate/src/modules/group/aminomessages.ts
+++ b/packages/stargate/src/modules/group/aminomessages.ts
@@ -1,4 +1,4 @@
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 export function createGroupAminoConverters(): AminoConverters {
   // Missing, see https://github.com/cosmos/cosmjs/issues/1441
diff --git a/packages/stargate/src/modules/ibc/aminomessages.spec.ts b/packages/stargate/src/modules/ibc/aminomessages.spec.ts
index c065b4028e..f18bc59e65 100644
--- a/packages/stargate/src/modules/ibc/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/ibc/aminomessages.spec.ts
@@ -1,8 +1,8 @@
 import { coin } from "@cosmjs/proto-signing";
 import { MsgTransfer } from "cosmjs-types/ibc/applications/transfer/v1/tx";
 
-import { AminoTypes } from "../../aminotypes";
-import { AminoMsgTransfer, createIbcAminoConverters } from "./aminomessages";
+import { AminoTypes } from "../../aminotypes.ts";
+import { AminoMsgTransfer, createIbcAminoConverters } from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("toAmino", () => {
diff --git a/packages/stargate/src/modules/ibc/aminomessages.ts b/packages/stargate/src/modules/ibc/aminomessages.ts
index a25e73009f..d9dea3890d 100644
--- a/packages/stargate/src/modules/ibc/aminomessages.ts
+++ b/packages/stargate/src/modules/ibc/aminomessages.ts
@@ -2,9 +2,9 @@
 import { AminoMsg, Coin, omitDefault } from "@cosmjs/amino";
 import { MsgTransfer } from "cosmjs-types/ibc/applications/transfer/v1/tx";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
-// https://github.com/cosmos/ibc-go/blob/07b6a97b67d17fd214a83764cbdb2c2c3daef445/modules/core/02-client/types/client.pb.go#L297-L312
+// https://github.com/cosmos/ibc-go/blob/07b6a97b67d17fd214a83764cbdb2c2c3daef445/modules/index/core/02-client/types/client.pb.go#L297-L312
 interface AminoHeight {
   /** 0 values must be omitted (https://github.com/cosmos/cosmos-sdk/blob/v0.42.7/x/ibc/core/02-client/types/client.pb.go#L252). */
   readonly revision_number?: string;
@@ -12,7 +12,7 @@ interface AminoHeight {
   readonly revision_height?: string;
 }
 
-// https://github.com/cosmos/ibc-go/blob/a4ca39c59f770a0b6948947d5178d5f0914c3a17/modules/apps/transfer/types/tx.pb.go#L37-L56
+// https://github.com/cosmos/ibc-go/blob/a4ca39c59f770a0b6948947d5178d5f0914c3a17/modules/index/apps/transfer/types/tx.pb.go#L37-L56
 /** Transfers fungible tokens (i.e Coins) between ICS20 enabled chains */
 export interface AminoMsgTransfer extends AminoMsg {
   readonly type: "cosmos-sdk/MsgTransfer";
diff --git a/packages/stargate/src/modules/ibc/queries.spec.ts b/packages/stargate/src/modules/ibc/queries.spec.ts
index 0ee0d53bb2..70f3edf6be 100644
--- a/packages/stargate/src/modules/ibc/queries.spec.ts
+++ b/packages/stargate/src/modules/ibc/queries.spec.ts
@@ -1,9 +1,9 @@
 import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 
-import { QueryClient } from "../../queryclient";
-import { simapp } from "../../testutils";
-import * as ibcTest from "./ibctestdata.spec";
-import { IbcExtension, setupIbcExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { simapp } from "../../testutils.ts";
+import * as ibcTest from "./ibctestdata.spec.ts";
+import { IbcExtension, setupIbcExtension } from "./queries.ts";
 
 async function makeClientWithIbc(rpcUrl: string): Promise<[QueryClient & IbcExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/ibc/queries.ts b/packages/stargate/src/modules/ibc/queries.ts
index 9ff7b4aaf2..d16bf6ff0e 100644
--- a/packages/stargate/src/modules/ibc/queries.ts
+++ b/packages/stargate/src/modules/ibc/queries.ts
@@ -46,7 +46,7 @@ import {
   ConsensusState as TendermintConsensusState,
 } from "cosmjs-types/ibc/lightclients/tendermint/v1/tendermint";
 
-import { createPagination, createProtobufRpcClient, longify, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, longify, QueryClient } from "../../queryclient/index.ts";
 
 function decodeTendermintClientStateAny(clientState: Any | undefined): TendermintClientState {
   if (clientState?.typeUrl !== "/ibc.lightclients.tendermint.v1.ClientState") {
diff --git a/packages/stargate/src/modules/index.ts b/packages/stargate/src/modules/index.ts
index 69ee868bf5..9a3c917cff 100644
--- a/packages/stargate/src/modules/index.ts
+++ b/packages/stargate/src/modules/index.ts
@@ -1,95 +1,95 @@
-export { type AuthExtension, setupAuthExtension } from "./auth/queries";
-export { createAuthzAminoConverters } from "./authz/aminomessages";
-export { authzTypes } from "./authz/messages";
-export { setupAuthzExtension } from "./authz/queries";
+export { type AuthExtension, setupAuthExtension } from "./auth/queries.ts";
+export { createAuthzAminoConverters } from "./authz/aminomessages.ts";
+export { authzTypes } from "./authz/messages.ts";
+export { setupAuthzExtension } from "./authz/queries.ts";
 export {
   type AminoMsgMultiSend,
   type AminoMsgSend,
   createBankAminoConverters,
   isAminoMsgMultiSend,
   isAminoMsgSend,
-} from "./bank/aminomessages";
-export { type MsgSendEncodeObject, bankTypes, isMsgSendEncodeObject } from "./bank/messages";
-export { type BankExtension, setupBankExtension } from "./bank/queries";
+} from "./bank/aminomessages.ts";
+export { type MsgSendEncodeObject, bankTypes, isMsgSendEncodeObject } from "./bank/messages.ts";
+export { type BankExtension, setupBankExtension } from "./bank/queries.ts";
 export {
   type AminoMsgVerifyInvariant,
   createCrysisAminoConverters,
   isAminoMsgVerifyInvariant,
-} from "./crisis/aminomessages";
+} from "./crisis/aminomessages.ts";
 export type {
   AminoMsgFundCommunityPool,
   AminoMsgSetWithdrawAddress,
   AminoMsgWithdrawDelegatorReward,
   AminoMsgWithdrawValidatorCommission,
-} from "./distribution/aminomessages";
+} from "./distribution/aminomessages.ts";
 export {
   createDistributionAminoConverters,
   isAminoMsgFundCommunityPool,
   isAminoMsgSetWithdrawAddress,
   isAminoMsgWithdrawDelegatorReward,
   isAminoMsgWithdrawValidatorCommission,
-} from "./distribution/aminomessages";
+} from "./distribution/aminomessages.ts";
 export {
   type MsgWithdrawDelegatorRewardEncodeObject,
   distributionTypes,
   isMsgWithdrawDelegatorRewardEncodeObject,
-} from "./distribution/messages";
-export { type DistributionExtension, setupDistributionExtension } from "./distribution/queries";
+} from "./distribution/messages.ts";
+export { type DistributionExtension, setupDistributionExtension } from "./distribution/queries.ts";
 export {
   type AminoMsgSubmitEvidence,
   createEvidenceAminoConverters,
   isAminoMsgSubmitEvidence,
-} from "./evidence/aminomessages";
-export { createFeegrantAminoConverters } from "./feegrant/aminomessages";
-export { feegrantTypes } from "./feegrant/messages";
-export { type FeegrantExtension, setupFeegrantExtension } from "./feegrant/queries";
+} from "./evidence/aminomessages.ts";
+export { createFeegrantAminoConverters } from "./feegrant/aminomessages.ts";
+export { feegrantTypes } from "./feegrant/messages.ts";
+export { type FeegrantExtension, setupFeegrantExtension } from "./feegrant/queries.ts";
 export type {
   AminoMsgDeposit,
   AminoMsgSubmitProposal,
   AminoMsgVote,
   AminoMsgVoteWeighted,
-} from "./gov/aminomessages";
+} from "./gov/aminomessages.ts";
 export {
   createGovAminoConverters,
   isAminoMsgDeposit,
   isAminoMsgSubmitProposal,
   isAminoMsgVote,
   isAminoMsgVoteWeighted,
-} from "./gov/aminomessages";
+} from "./gov/aminomessages.ts";
 export type {
   MsgDepositEncodeObject,
   MsgSubmitProposalEncodeObject,
   MsgVoteEncodeObject,
   MsgVoteWeightedEncodeObject,
-} from "./gov/messages";
+} from "./gov/messages.ts";
 export {
   govTypes,
   isMsgDepositEncodeObject,
   isMsgSubmitProposalEncodeObject,
   isMsgVoteEncodeObject,
   isMsgVoteWeightedEncodeObject,
-} from "./gov/messages";
-export type { GovExtension, GovParamsType, GovProposalId } from "./gov/queries";
-export { setupGovExtension } from "./gov/queries";
-export { createGroupAminoConverters } from "./group/aminomessages";
-export { groupTypes } from "./group/messages";
-export { type AminoMsgTransfer, createIbcAminoConverters, isAminoMsgTransfer } from "./ibc/aminomessages";
-export { type MsgTransferEncodeObject, ibcTypes, isMsgTransferEncodeObject } from "./ibc/messages";
-export { type IbcExtension, setupIbcExtension } from "./ibc/queries";
-export { type MintExtension, type MintParams, setupMintExtension } from "./mint/queries";
+} from "./gov/messages.ts";
+export type { GovExtension, GovParamsType, GovProposalId } from "./gov/queries.ts";
+export { setupGovExtension } from "./gov/queries.ts";
+export { createGroupAminoConverters } from "./group/aminomessages.ts";
+export { groupTypes } from "./group/messages.ts";
+export { type AminoMsgTransfer, createIbcAminoConverters, isAminoMsgTransfer } from "./ibc/aminomessages.ts";
+export { type MsgTransferEncodeObject, ibcTypes, isMsgTransferEncodeObject } from "./ibc/messages.ts";
+export { type IbcExtension, setupIbcExtension } from "./ibc/queries.ts";
+export { type MintExtension, type MintParams, setupMintExtension } from "./mint/queries.ts";
 export {
   type AminoMsgUnjail,
   createSlashingAminoConverters,
   isAminoMsgUnjail,
-} from "./slashing/aminomessages";
-export { type SlashingExtension, setupSlashingExtension } from "./slashing/queries";
+} from "./slashing/aminomessages.ts";
+export { type SlashingExtension, setupSlashingExtension } from "./slashing/queries.ts";
 export type {
   AminoMsgBeginRedelegate,
   AminoMsgCreateValidator,
   AminoMsgDelegate,
   AminoMsgEditValidator,
   AminoMsgUndelegate,
-} from "./staking/aminomessages";
+} from "./staking/aminomessages.ts";
 export {
   createStakingAminoConverters,
   isAminoMsgBeginRedelegate,
@@ -97,7 +97,7 @@ export {
   isAminoMsgDelegate,
   isAminoMsgEditValidator,
   isAminoMsgUndelegate,
-} from "./staking/aminomessages";
+} from "./staking/aminomessages.ts";
 export type {
   MsgBeginRedelegateEncodeObject,
   MsgCancelUnbondingDelegationEncodeObject,
@@ -105,7 +105,7 @@ export type {
   MsgDelegateEncodeObject,
   MsgEditValidatorEncodeObject,
   MsgUndelegateEncodeObject,
-} from "./staking/messages";
+} from "./staking/messages.ts";
 export {
   isMsgBeginRedelegateEncodeObject,
   isMsgCancelUnbondingDelegationEncodeObject,
@@ -114,12 +114,12 @@ export {
   isMsgEditValidatorEncodeObject,
   isMsgUndelegateEncodeObject,
   stakingTypes,
-} from "./staking/messages";
-export { type StakingExtension, setupStakingExtension } from "./staking/queries";
-export { type TxExtension, setupTxExtension } from "./tx/queries";
+} from "./staking/messages.ts";
+export { type StakingExtension, setupStakingExtension } from "./staking/queries.ts";
+export { type TxExtension, setupTxExtension } from "./tx/queries.ts";
 export {
   type AminoMsgCreateVestingAccount,
   createVestingAminoConverters,
   isAminoMsgCreateVestingAccount,
-} from "./vesting/aminomessages";
-export { vestingTypes } from "./vesting/messages";
+} from "./vesting/aminomessages.ts";
+export { vestingTypes } from "./vesting/messages.ts";
diff --git a/packages/stargate/src/modules/mint/queries.spec.ts b/packages/stargate/src/modules/mint/queries.spec.ts
index 84cd2447a1..18f5ad3feb 100644
--- a/packages/stargate/src/modules/mint/queries.spec.ts
+++ b/packages/stargate/src/modules/mint/queries.spec.ts
@@ -1,8 +1,8 @@
 import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 
-import { QueryClient } from "../../queryclient";
-import { simapp, simappEnabled } from "../../testutils";
-import { MintExtension, setupMintExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { simapp, simappEnabled } from "../../testutils.ts";
+import { MintExtension, setupMintExtension } from "./queries.ts";
 
 async function makeClientWithMint(rpcUrl: string): Promise<[QueryClient & MintExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/mint/queries.ts b/packages/stargate/src/modules/mint/queries.ts
index 8d7b28e166..1946aace3c 100644
--- a/packages/stargate/src/modules/mint/queries.ts
+++ b/packages/stargate/src/modules/mint/queries.ts
@@ -3,7 +3,11 @@ import { assert } from "@cosmjs/utils";
 import { Params } from "cosmjs-types/cosmos/mint/v1beta1/mint";
 import { QueryClientImpl } from "cosmjs-types/cosmos/mint/v1beta1/query";
 
-import { createProtobufRpcClient, decodeCosmosSdkDecFromProto, QueryClient } from "../../queryclient";
+import {
+  createProtobufRpcClient,
+  decodeCosmosSdkDecFromProto,
+  QueryClient,
+} from "../../queryclient/index.ts";
 
 /**
  * Like Params from "cosmjs-types/cosmos/mint/v1beta1/mint"
diff --git a/packages/stargate/src/modules/slashing/aminomessages.ts b/packages/stargate/src/modules/slashing/aminomessages.ts
index ccb535da17..a77d2b8aba 100644
--- a/packages/stargate/src/modules/slashing/aminomessages.ts
+++ b/packages/stargate/src/modules/slashing/aminomessages.ts
@@ -1,7 +1,7 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { AminoMsg } from "@cosmjs/amino";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 // See https://github.com/cosmos/cosmos-sdk/blob/v0.45.1/proto/cosmos/slashing/v1beta1/tx.proto
 
diff --git a/packages/stargate/src/modules/slashing/queries.spec.ts b/packages/stargate/src/modules/slashing/queries.spec.ts
index f063b6b3ff..24919b27e9 100644
--- a/packages/stargate/src/modules/slashing/queries.spec.ts
+++ b/packages/stargate/src/modules/slashing/queries.spec.ts
@@ -1,8 +1,8 @@
 import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 
-import { QueryClient } from "../../queryclient";
-import { simapp, simappEnabled } from "../../testutils";
-import { setupSlashingExtension, SlashingExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { simapp, simappEnabled } from "../../testutils.ts";
+import { setupSlashingExtension, SlashingExtension } from "./queries.ts";
 
 async function makeClientWithSlashing(
   rpcUrl: string,
diff --git a/packages/stargate/src/modules/slashing/queries.ts b/packages/stargate/src/modules/slashing/queries.ts
index fae3fc5f22..7ef6b09f46 100644
--- a/packages/stargate/src/modules/slashing/queries.ts
+++ b/packages/stargate/src/modules/slashing/queries.ts
@@ -5,7 +5,7 @@ import {
   QuerySigningInfosResponse,
 } from "cosmjs-types/cosmos/slashing/v1beta1/query";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface SlashingExtension {
   readonly slashing: {
diff --git a/packages/stargate/src/modules/staking/aminomessages.spec.ts b/packages/stargate/src/modules/staking/aminomessages.spec.ts
index ebe51cdbce..6c11b1ec8d 100644
--- a/packages/stargate/src/modules/staking/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/staking/aminomessages.spec.ts
@@ -10,7 +10,7 @@ import {
   MsgUndelegate,
 } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { AminoTypes } from "../../aminotypes";
+import { AminoTypes } from "../../aminotypes.ts";
 import {
   AminoMsgBeginRedelegate,
   AminoMsgCancelUnbondingDelegation,
@@ -20,7 +20,7 @@ import {
   AminoMsgUndelegate,
   createStakingAminoConverters,
   protoDecimalToJson,
-} from "./aminomessages";
+} from "./aminomessages.ts";
 
 describe("AminoTypes", () => {
   describe("protoDecimalToJson", () => {
diff --git a/packages/stargate/src/modules/staking/aminomessages.ts b/packages/stargate/src/modules/staking/aminomessages.ts
index 450636be53..5fbf69e0b4 100644
--- a/packages/stargate/src/modules/staking/aminomessages.ts
+++ b/packages/stargate/src/modules/staking/aminomessages.ts
@@ -12,7 +12,7 @@ import {
   MsgUndelegate,
 } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { AminoConverter } from "../..";
+import { AminoConverter } from "../../index.ts";
 
 /** The initial commission rates to be used for creating a validator */
 interface CommissionRates {
@@ -93,7 +93,7 @@ export function isAminoMsgEditValidator(msg: AminoMsg): msg is AminoMsgEditValid
 /**
  * Performs a delegation from a delegate to a validator.
  *
- * @see https://docs.cosmos.network/main/build/modules/staking#msgdelegate
+ * @see https://docs.cosmos.network/main/build/modules/index/staking#msgdelegate
  */
 export interface AminoMsgDelegate extends AminoMsg {
   readonly type: "cosmos-sdk/MsgDelegate";
diff --git a/packages/stargate/src/modules/staking/messages.spec.ts b/packages/stargate/src/modules/staking/messages.spec.ts
index 32451a26cd..8d758aba06 100644
--- a/packages/stargate/src/modules/staking/messages.spec.ts
+++ b/packages/stargate/src/modules/staking/messages.spec.ts
@@ -3,9 +3,9 @@ import { Random } from "@cosmjs/crypto";
 import { fromBech32, toBase64, toBech32 } from "@cosmjs/encoding";
 import { DirectSecp256k1HdWallet, encodePubkey } from "@cosmjs/proto-signing";
 
-import { calculateFee } from "../../fee";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
+import { calculateFee } from "../../fee.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
 import {
   defaultGasPrice,
   defaultSigningClientOptions,
@@ -13,8 +13,8 @@ import {
   simapp,
   simapp50Enabled,
   simappEnabled,
-} from "../../testutils";
-import { MsgCreateValidatorEncodeObject, MsgEditValidatorEncodeObject } from "./messages";
+} from "../../testutils.ts";
+import { MsgCreateValidatorEncodeObject, MsgEditValidatorEncodeObject } from "./messages.ts";
 
 function changePrefix(address: string, newPrefix: string): string {
   return toBech32(newPrefix, fromBech32(address).data);
diff --git a/packages/stargate/src/modules/staking/queries.spec.ts b/packages/stargate/src/modules/staking/queries.spec.ts
index 703adc6271..fdd27525ce 100644
--- a/packages/stargate/src/modules/staking/queries.spec.ts
+++ b/packages/stargate/src/modules/staking/queries.spec.ts
@@ -3,12 +3,12 @@ import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 import { sleep } from "@cosmjs/utils";
 import { MsgDelegate, MsgUndelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { QueryClient } from "../../queryclient";
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
-import { defaultSigningClientOptions, faucet, simapp, simappEnabled, validator } from "../../testutils";
-import { MsgDelegateEncodeObject, MsgUndelegateEncodeObject } from "./messages";
-import { setupStakingExtension, StakingExtension } from "./queries";
+import { QueryClient } from "../../queryclient/index.ts";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
+import { defaultSigningClientOptions, faucet, simapp, simappEnabled, validator } from "../../testutils.ts";
+import { MsgDelegateEncodeObject, MsgUndelegateEncodeObject } from "./messages.ts";
+import { setupStakingExtension, StakingExtension } from "./queries.ts";
 
 async function makeClientWithStaking(rpcUrl: string): Promise<[QueryClient & StakingExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/staking/queries.ts b/packages/stargate/src/modules/staking/queries.ts
index b565718518..e76526700b 100644
--- a/packages/stargate/src/modules/staking/queries.ts
+++ b/packages/stargate/src/modules/staking/queries.ts
@@ -17,7 +17,7 @@ import {
 } from "cosmjs-types/cosmos/staking/v1beta1/query";
 import { BondStatus } from "cosmjs-types/cosmos/staking/v1beta1/staking";
 
-import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createPagination, createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 // It's an enum in Go and a string in the protobuf API. "BOND_STATUS_UNSPECIFIED"
 // is excluded and "" is supported instead 🤷.
diff --git a/packages/stargate/src/modules/tx/queries.spec.ts b/packages/stargate/src/modules/tx/queries.spec.ts
index 686aabc322..07ce647e69 100644
--- a/packages/stargate/src/modules/tx/queries.spec.ts
+++ b/packages/stargate/src/modules/tx/queries.spec.ts
@@ -3,9 +3,9 @@ import { CometClient, connectComet } from "@cosmjs/tendermint-rpc";
 import { assertDefined, sleep } from "@cosmjs/utils";
 import { MsgDelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 
-import { QueryClient } from "../../queryclient";
-import { defaultRegistryTypes, SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess, StargateClient } from "../../stargateclient";
+import { QueryClient } from "../../queryclient/index.ts";
+import { defaultRegistryTypes, SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess, StargateClient } from "../../stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
@@ -13,8 +13,8 @@ import {
   simapp,
   simappEnabled,
   validator,
-} from "../../testutils";
-import { setupTxExtension, TxExtension } from "./queries";
+} from "../../testutils.ts";
+import { setupTxExtension, TxExtension } from "./queries.ts";
 
 async function makeClientWithTx(rpcUrl: string): Promise<[QueryClient & TxExtension, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/modules/tx/queries.ts b/packages/stargate/src/modules/tx/queries.ts
index c3975efdc8..922a25adf0 100644
--- a/packages/stargate/src/modules/tx/queries.ts
+++ b/packages/stargate/src/modules/tx/queries.ts
@@ -11,7 +11,7 @@ import {
 import { AuthInfo, Fee, Tx, TxBody } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { createProtobufRpcClient, QueryClient } from "../../queryclient";
+import { createProtobufRpcClient, QueryClient } from "../../queryclient/index.ts";
 
 export interface TxExtension {
   readonly tx: {
diff --git a/packages/stargate/src/modules/vesting/aminomessages.spec.ts b/packages/stargate/src/modules/vesting/aminomessages.spec.ts
index 56b212f46c..5be805e659 100644
--- a/packages/stargate/src/modules/vesting/aminomessages.spec.ts
+++ b/packages/stargate/src/modules/vesting/aminomessages.spec.ts
@@ -1,8 +1,8 @@
 import { coins } from "@cosmjs/amino";
 import { MsgCreateVestingAccount } from "cosmjs-types/cosmos/vesting/v1beta1/tx";
 
-import { AminoTypes } from "../../aminotypes";
-import { AminoMsgCreateVestingAccount, createVestingAminoConverters } from "./aminomessages";
+import { AminoTypes } from "../../aminotypes.ts";
+import { AminoMsgCreateVestingAccount, createVestingAminoConverters } from "./aminomessages.ts";
 
 describe("vesting Amino messages", () => {
   describe("toAmino", () => {
diff --git a/packages/stargate/src/modules/vesting/aminomessages.ts b/packages/stargate/src/modules/vesting/aminomessages.ts
index 55471e1b04..6f6dbe842c 100644
--- a/packages/stargate/src/modules/vesting/aminomessages.ts
+++ b/packages/stargate/src/modules/vesting/aminomessages.ts
@@ -2,7 +2,7 @@
 import { AminoMsg, Coin } from "@cosmjs/amino";
 import { MsgCreateVestingAccount } from "cosmjs-types/cosmos/vesting/v1beta1/tx";
 
-import { AminoConverters } from "../../aminotypes";
+import { AminoConverters } from "../../aminotypes.ts";
 
 export interface AminoMsgCreateVestingAccount extends AminoMsg {
   readonly type: "cosmos-sdk/MsgCreateVestingAccount";
diff --git a/packages/stargate/src/modules/vesting/messages.spec.ts b/packages/stargate/src/modules/vesting/messages.spec.ts
index 41485bd524..20b21b5ba9 100644
--- a/packages/stargate/src/modules/vesting/messages.spec.ts
+++ b/packages/stargate/src/modules/vesting/messages.spec.ts
@@ -2,15 +2,15 @@ import { coin, coins, Secp256k1HdWallet } from "@cosmjs/amino";
 import { DirectSecp256k1HdWallet } from "@cosmjs/proto-signing";
 import { MsgCreateVestingAccount } from "cosmjs-types/cosmos/vesting/v1beta1/tx";
 
-import { SigningStargateClient } from "../../signingstargateclient";
-import { assertIsDeliverTxSuccess } from "../../stargateclient";
+import { SigningStargateClient } from "../../signingstargateclient.ts";
+import { assertIsDeliverTxSuccess } from "../../stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
   makeRandomAddress,
   simapp,
   simappEnabled,
-} from "../../testutils";
+} from "../../testutils.ts";
 
 (simappEnabled ? describe : xdescribe)("vesting messages", () => {
   describe("MsgCreateVestingAccount", () => {
diff --git a/packages/stargate/src/multisignature.spec.ts b/packages/stargate/src/multisignature.spec.ts
index efd58ffbd7..25dd39b49e 100644
--- a/packages/stargate/src/multisignature.spec.ts
+++ b/packages/stargate/src/multisignature.spec.ts
@@ -9,11 +9,11 @@ import { coins } from "@cosmjs/proto-signing";
 import { assert } from "@cosmjs/utils";
 import { MsgSend } from "cosmjs-types/cosmos/bank/v1beta1/tx";
 
-import { MsgSendEncodeObject } from "./modules";
-import { makeCompactBitArray, makeMultisignedTxBytes } from "./multisignature";
-import { SignerData, SigningStargateClient } from "./signingstargateclient";
-import { assertIsDeliverTxSuccess, StargateClient } from "./stargateclient";
-import { faucet, simapp, simappEnabled } from "./testutils";
+import { MsgSendEncodeObject } from "./modules/index.ts";
+import { makeCompactBitArray, makeMultisignedTxBytes } from "./multisignature.ts";
+import { SignerData, SigningStargateClient } from "./signingstargateclient.ts";
+import { assertIsDeliverTxSuccess, StargateClient } from "./stargateclient.ts";
+import { faucet, simapp, simappEnabled } from "./testutils.ts";
 
 describe("multisignature", () => {
   describe("makeCompactBitArray", () => {
diff --git a/packages/stargate/src/queryclient/index.ts b/packages/stargate/src/queryclient/index.ts
index 283d5cc09d..19664a1f9c 100644
--- a/packages/stargate/src/queryclient/index.ts
+++ b/packages/stargate/src/queryclient/index.ts
@@ -1,8 +1,8 @@
-export { type QueryAbciResponse, type QueryStoreResponse, QueryClient } from "./queryclient";
+export { type QueryAbciResponse, type QueryStoreResponse, QueryClient } from "./queryclient.ts";
 export {
   type ProtobufRpcClient,
   createPagination,
   createProtobufRpcClient,
   decodeCosmosSdkDecFromProto,
   longify,
-} from "./utils";
+} from "./utils.ts";
diff --git a/packages/stargate/src/queryclient/queryclient.spec.ts b/packages/stargate/src/queryclient/queryclient.spec.ts
index ca363582e8..40e2b5e419 100644
--- a/packages/stargate/src/queryclient/queryclient.spec.ts
+++ b/packages/stargate/src/queryclient/queryclient.spec.ts
@@ -9,7 +9,7 @@ import {
   QueryBalanceResponse,
 } from "cosmjs-types/cosmos/bank/v1beta1/query";
 
-import { SigningStargateClient } from "../signingstargateclient";
+import { SigningStargateClient } from "../signingstargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
@@ -17,8 +17,8 @@ import {
   simapp,
   simappEnabled,
   unused,
-} from "../testutils";
-import { QueryClient } from "./queryclient";
+} from "../testutils.ts";
+import { QueryClient } from "./queryclient.ts";
 
 async function makeClient(rpcUrl: string): Promise<[QueryClient, CometClient]> {
   const cometClient = await connectComet(rpcUrl);
diff --git a/packages/stargate/src/queryclient/utils.spec.ts b/packages/stargate/src/queryclient/utils.spec.ts
index 703efca4c7..a9f4dc5ad8 100644
--- a/packages/stargate/src/queryclient/utils.spec.ts
+++ b/packages/stargate/src/queryclient/utils.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { decodeCosmosSdkDecFromProto } from "./utils";
+import { decodeCosmosSdkDecFromProto } from "./utils.ts";
 
 describe("utils", () => {
   describe("decodeCosmosSdkDecFromProto", () => {
diff --git a/packages/stargate/src/queryclient/utils.ts b/packages/stargate/src/queryclient/utils.ts
index d32764bcfe..9c7d6ca74b 100644
--- a/packages/stargate/src/queryclient/utils.ts
+++ b/packages/stargate/src/queryclient/utils.ts
@@ -2,7 +2,7 @@ import { fromAscii, fromBech32 } from "@cosmjs/encoding";
 import { Decimal, Uint64 } from "@cosmjs/math";
 import { PageRequest } from "cosmjs-types/cosmos/base/query/v1beta1/pagination";
 
-import { QueryClient } from "./queryclient";
+import { QueryClient } from "./queryclient.ts";
 
 /**
  * Takes a bech32 encoded address and returns the data part. The prefix is ignored and discarded.
diff --git a/packages/stargate/src/signingstargateclient.spec.ts b/packages/stargate/src/signingstargateclient.spec.ts
index af2156547d..f99551e9a2 100644
--- a/packages/stargate/src/signingstargateclient.spec.ts
+++ b/packages/stargate/src/signingstargateclient.spec.ts
@@ -20,20 +20,20 @@ import { MsgDelegate } from "cosmjs-types/cosmos/staking/v1beta1/tx";
 import { AuthInfo, TxBody, TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { Any } from "cosmjs-types/google/protobuf/any";
 
-import { AminoTypes } from "./aminotypes";
+import { AminoTypes } from "./aminotypes.ts";
 import {
   AminoMsgDelegate,
   MsgDelegateEncodeObject,
   MsgSendEncodeObject,
   setupFeegrantExtension,
-} from "./modules";
-import { QueryClient } from "./queryclient";
+} from "./modules/index.ts";
+import { QueryClient } from "./queryclient/index.ts";
 import {
   PrivateSigningStargateClient,
   SigningStargateClient,
   SigningStargateClientOptions,
-} from "./signingstargateclient";
-import { assertIsDeliverTxFailure, assertIsDeliverTxSuccess, isDeliverTxFailure } from "./stargateclient";
+} from "./signingstargateclient.ts";
+import { assertIsDeliverTxFailure, assertIsDeliverTxSuccess, isDeliverTxFailure } from "./stargateclient.ts";
 import {
   defaultGasPrice,
   defaultSendFee,
@@ -46,7 +46,7 @@ import {
   simapp50Enabled,
   simappEnabled,
   validator,
-} from "./testutils";
+} from "./testutils.ts";
 
 (simappEnabled ? describe : xdescribe)("SigningStargateClient", () => {
   describe("constructor", () => {
diff --git a/packages/stargate/src/signingstargateclient.ts b/packages/stargate/src/signingstargateclient.ts
index 2ba6e10633..5cbf552b12 100644
--- a/packages/stargate/src/signingstargateclient.ts
+++ b/packages/stargate/src/signingstargateclient.ts
@@ -22,8 +22,8 @@ import { TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 import { MsgTransfer } from "cosmjs-types/ibc/applications/transfer/v1/tx";
 import { Height } from "cosmjs-types/ibc/core/client/v1/client";
 
-import { AminoConverters, AminoTypes } from "./aminotypes";
-import { calculateFee, GasPrice } from "./fee";
+import { AminoConverters, AminoTypes } from "./aminotypes.ts";
+import { calculateFee, GasPrice } from "./fee.ts";
 import {
   authzTypes,
   bankTypes,
@@ -47,8 +47,8 @@ import {
   MsgWithdrawDelegatorRewardEncodeObject,
   stakingTypes,
   vestingTypes,
-} from "./modules";
-import { DeliverTxResponse, StargateClient, StargateClientOptions } from "./stargateclient";
+} from "./modules/index.ts";
+import { DeliverTxResponse, StargateClient, StargateClientOptions } from "./stargateclient.ts";
 
 export const defaultRegistryTypes: ReadonlyArray<[string, GeneratedType]> = [
   ["/cosmos.base.v1beta1.Coin", Coin],
diff --git a/packages/stargate/src/stargateclient.searchtx.spec.ts b/packages/stargate/src/stargateclient.searchtx.spec.ts
index 6611cf059e..675e48e3da 100644
--- a/packages/stargate/src/stargateclient.searchtx.spec.ts
+++ b/packages/stargate/src/stargateclient.searchtx.spec.ts
@@ -14,8 +14,13 @@ import { MsgSendResponse } from "cosmjs-types/cosmos/bank/v1beta1/tx";
 import { Coin } from "cosmjs-types/cosmos/base/v1beta1/coin";
 import { TxRaw } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { isMsgSendEncodeObject } from "./modules";
-import { DeliverTxResponse, isDeliverTxFailure, isDeliverTxSuccess, StargateClient } from "./stargateclient";
+import { isMsgSendEncodeObject } from "./modules/index.ts";
+import {
+  DeliverTxResponse,
+  isDeliverTxFailure,
+  isDeliverTxSuccess,
+  StargateClient,
+} from "./stargateclient.ts";
 import {
   defaultSigningClientOptions,
   faucet,
@@ -23,7 +28,7 @@ import {
   makeRandomAddress,
   simapp,
   simappEnabled,
-} from "./testutils";
+} from "./testutils.ts";
 
 interface TestTxSend {
   readonly sender: string;
diff --git a/packages/stargate/src/stargateclient.spec.ts b/packages/stargate/src/stargateclient.spec.ts
index 1a03c0af35..bf19333d9b 100644
--- a/packages/stargate/src/stargateclient.spec.ts
+++ b/packages/stargate/src/stargateclient.spec.ts
@@ -21,7 +21,7 @@ import {
   PrivateStargateClient,
   StargateClient,
   TimeoutError,
-} from "./stargateclient";
+} from "./stargateclient.ts";
 import {
   faucet,
   makeRandomAddress,
@@ -35,7 +35,7 @@ import {
   tendermintIdMatcher,
   unused,
   validator,
-} from "./testutils";
+} from "./testutils.ts";
 
 const resultFailure: DeliverTxResponse = {
   code: 5,
diff --git a/packages/stargate/src/stargateclient.ts b/packages/stargate/src/stargateclient.ts
index a4be158f7c..3e33181281 100644
--- a/packages/stargate/src/stargateclient.ts
+++ b/packages/stargate/src/stargateclient.ts
@@ -8,8 +8,8 @@ import { Coin } from "cosmjs-types/cosmos/base/v1beta1/coin";
 import { QueryDelegatorDelegationsResponse } from "cosmjs-types/cosmos/staking/v1beta1/query";
 import { DelegationResponse } from "cosmjs-types/cosmos/staking/v1beta1/staking";
 
-import { Account, accountFromAny, AccountParser } from "./accounts";
-import { Event, fromTendermintEvent } from "./events";
+import { Account, accountFromAny, AccountParser } from "./accounts.ts";
+import { Event, fromTendermintEvent } from "./events.ts";
 import {
   AuthExtension,
   BankExtension,
@@ -19,9 +19,9 @@ import {
   setupTxExtension,
   StakingExtension,
   TxExtension,
-} from "./modules";
-import { QueryClient } from "./queryclient";
-import { isSearchTxQueryArray, SearchTxQuery } from "./search";
+} from "./modules/index.ts";
+import { QueryClient } from "./queryclient/index.ts";
+import { isSearchTxQueryArray, SearchTxQuery } from "./search.ts";
 
 export class TimeoutError extends Error {
   public readonly txId: string;
diff --git a/packages/stargate/src/testutils.ts b/packages/stargate/src/testutils.ts
index b9a80886e3..11fd08e113 100644
--- a/packages/stargate/src/testutils.ts
+++ b/packages/stargate/src/testutils.ts
@@ -12,8 +12,8 @@ import { assertDefinedAndNotNull } from "@cosmjs/utils";
 import { SignMode } from "cosmjs-types/cosmos/tx/signing/v1beta1/signing";
 import { AuthInfo, SignDoc, TxBody } from "cosmjs-types/cosmos/tx/v1beta1/tx";
 
-import { calculateFee, GasPrice } from "./fee";
-import { SigningStargateClientOptions } from "./signingstargateclient";
+import { calculateFee, GasPrice } from "./fee.ts";
+import { SigningStargateClientOptions } from "./signingstargateclient.ts";
 
 export const simapp47Enabled: boolean = !!globalThis.process?.env.SIMAPP47_ENABLED;
 export const simapp50Enabled: boolean = !!globalThis.process?.env.SIMAPP50_ENABLED;
diff --git a/packages/stream/src/concat.spec.ts b/packages/stream/src/concat.spec.ts
index 5b53cb1394..2c8dd9ea06 100644
--- a/packages/stream/src/concat.spec.ts
+++ b/packages/stream/src/concat.spec.ts
@@ -1,6 +1,6 @@
 import { Producer, Stream } from "xstream";
 
-import { concat } from "./concat";
+import { concat } from "./concat.ts";
 
 async function producerIsStopped(): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, 50));
diff --git a/packages/stream/src/defaultvalueproducer.spec.ts b/packages/stream/src/defaultvalueproducer.spec.ts
index b87567faca..8d4f34fab8 100644
--- a/packages/stream/src/defaultvalueproducer.spec.ts
+++ b/packages/stream/src/defaultvalueproducer.spec.ts
@@ -1,6 +1,6 @@
 import { Stream } from "xstream";
 
-import { DefaultValueProducer } from "./defaultvalueproducer";
+import { DefaultValueProducer } from "./defaultvalueproducer.ts";
 
 async function oneTickLater(): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, 0));
diff --git a/packages/stream/src/dropduplicates.spec.ts b/packages/stream/src/dropduplicates.spec.ts
index 380ff9724a..4db2a8a81f 100644
--- a/packages/stream/src/dropduplicates.spec.ts
+++ b/packages/stream/src/dropduplicates.spec.ts
@@ -1,6 +1,6 @@
 import { Stream } from "xstream";
 
-import { dropDuplicates } from "./dropduplicates";
+import { dropDuplicates } from "./dropduplicates.ts";
 
 describe("dropDuplicates", () => {
   it("can be created", () => {
diff --git a/packages/stream/src/index.ts b/packages/stream/src/index.ts
index 0f919a4587..3818f09cf4 100644
--- a/packages/stream/src/index.ts
+++ b/packages/stream/src/index.ts
@@ -1,6 +1,6 @@
-export { concat } from "./concat";
-export { type DefaultValueProducerCallsbacks, DefaultValueProducer } from "./defaultvalueproducer";
-export { type SameTypeStreamOperator, dropDuplicates } from "./dropduplicates";
-export { firstEvent, fromListPromise, toListPromise } from "./promise";
-export * from "./reducer";
-export { ValueAndUpdates } from "./valueandupdates";
+export { concat } from "./concat.ts";
+export { type DefaultValueProducerCallsbacks, DefaultValueProducer } from "./defaultvalueproducer.ts";
+export { type SameTypeStreamOperator, dropDuplicates } from "./dropduplicates.ts";
+export { firstEvent, fromListPromise, toListPromise } from "./promise.ts";
+export * from "./reducer.ts";
+export { ValueAndUpdates } from "./valueandupdates.ts";
diff --git a/packages/stream/src/promise.spec.ts b/packages/stream/src/promise.spec.ts
index 09326eb150..cd48a2e7fd 100644
--- a/packages/stream/src/promise.spec.ts
+++ b/packages/stream/src/promise.spec.ts
@@ -1,7 +1,7 @@
 import { Producer, Stream } from "xstream";
 
-import { firstEvent, fromListPromise, toListPromise } from "./promise";
-import { asArray, countStream } from "./reducer";
+import { firstEvent, fromListPromise, toListPromise } from "./promise.ts";
+import { asArray, countStream } from "./reducer.ts";
 
 async function oneTickLater(): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, 0));
diff --git a/packages/stream/src/reducer.spec.ts b/packages/stream/src/reducer.spec.ts
index 549dc2084f..a7fbf1a5af 100644
--- a/packages/stream/src/reducer.spec.ts
+++ b/packages/stream/src/reducer.spec.ts
@@ -1,6 +1,6 @@
 import { Stream } from "xstream";
 
-import { asArray, countStream, lastValue } from "./reducer";
+import { asArray, countStream, lastValue } from "./reducer.ts";
 
 describe("Test stream helpers", () => {
   it("readIntoArray returns input", async () => {
diff --git a/packages/stream/src/valueandupdates.spec.ts b/packages/stream/src/valueandupdates.spec.ts
index 2c84ef3dac..22e6746496 100644
--- a/packages/stream/src/valueandupdates.spec.ts
+++ b/packages/stream/src/valueandupdates.spec.ts
@@ -1,7 +1,7 @@
 import { Listener } from "xstream";
 
-import { DefaultValueProducer } from "./defaultvalueproducer";
-import { ValueAndUpdates } from "./valueandupdates";
+import { DefaultValueProducer } from "./defaultvalueproducer.ts";
+import { ValueAndUpdates } from "./valueandupdates.ts";
 
 describe("ValueAndUpdates", () => {
   it("can be constructed", () => {
diff --git a/packages/stream/src/valueandupdates.ts b/packages/stream/src/valueandupdates.ts
index b278561d02..3653bcc951 100644
--- a/packages/stream/src/valueandupdates.ts
+++ b/packages/stream/src/valueandupdates.ts
@@ -1,6 +1,6 @@
 import { MemoryStream } from "xstream";
 
-import { DefaultValueProducer } from "./defaultvalueproducer";
+import { DefaultValueProducer } from "./defaultvalueproducer.ts";
 
 export type SearchFunction<T> = (value: T) => boolean;
 
diff --git a/packages/tendermint-rpc/src/addresses.spec.ts b/packages/tendermint-rpc/src/addresses.spec.ts
index f75c28fd2d..f23383e8e8 100644
--- a/packages/tendermint-rpc/src/addresses.spec.ts
+++ b/packages/tendermint-rpc/src/addresses.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { pubkeyToAddress, pubkeyToRawAddress } from "./addresses";
+import { pubkeyToAddress, pubkeyToRawAddress } from "./addresses.ts";
 
 // Test values from https://github.com/informalsystems/tendermint-rs/blob/v0.18.1/tendermint/src/account.rs#L153-L192
 
diff --git a/packages/tendermint-rpc/src/comet1/adaptor/index.ts b/packages/tendermint-rpc/src/comet1/adaptor/index.ts
index 38e924802f..687e85be3a 100644
--- a/packages/tendermint-rpc/src/comet1/adaptor/index.ts
+++ b/packages/tendermint-rpc/src/comet1/adaptor/index.ts
@@ -1,2 +1,2 @@
-export { Params } from "./requests";
-export { Responses } from "./responses";
+export { Params } from "./requests.ts";
+export { Responses } from "./responses.ts";
diff --git a/packages/tendermint-rpc/src/comet1/adaptor/requests.ts b/packages/tendermint-rpc/src/comet1/adaptor/requests.ts
index c2ece2617e..229a92c39d 100644
--- a/packages/tendermint-rpc/src/comet1/adaptor/requests.ts
+++ b/packages/tendermint-rpc/src/comet1/adaptor/requests.ts
@@ -2,10 +2,10 @@
 import { toBase64, toHex } from "@cosmjs/encoding";
 import { JsonRpcRequest } from "@cosmjs/json-rpc";
 
-import { smallIntToApi } from "../../inthelpers";
-import { createJsonRpcRequest } from "../../jsonrpc";
-import { may } from "../encodings";
-import * as requests from "../requests";
+import { smallIntToApi } from "../../inthelpers.ts";
+import { createJsonRpcRequest } from "../../jsonrpc.ts";
+import { may } from "../encodings.ts";
+import * as requests from "../requests.ts";
 
 interface HeightParam {
   readonly height?: number;
diff --git a/packages/tendermint-rpc/src/comet1/adaptor/responses.spec.ts b/packages/tendermint-rpc/src/comet1/adaptor/responses.spec.ts
index fee08621cd..024b34a36e 100644
--- a/packages/tendermint-rpc/src/comet1/adaptor/responses.spec.ts
+++ b/packages/tendermint-rpc/src/comet1/adaptor/responses.spec.ts
@@ -8,7 +8,7 @@ import {
   decodeValidatorGenesis,
   decodeValidatorInfo,
   decodeValidatorUpdate,
-} from "./responses";
+} from "./responses.ts";
 
 describe("Responses", () => {
   describe("decodeEvent", () => {
diff --git a/packages/tendermint-rpc/src/comet1/adaptor/responses.ts b/packages/tendermint-rpc/src/comet1/adaptor/responses.ts
index 203654e5ca..bb0cdff278 100644
--- a/packages/tendermint-rpc/src/comet1/adaptor/responses.ts
+++ b/packages/tendermint-rpc/src/comet1/adaptor/responses.ts
@@ -3,8 +3,8 @@ import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { JsonRpcSuccessResponse } from "@cosmjs/json-rpc";
 import { assert } from "@cosmjs/utils";
 
-import { fromRfc3339WithNanoseconds } from "../../dates";
-import { apiToBigInt, apiToSmallInt } from "../../inthelpers";
+import { fromRfc3339WithNanoseconds } from "../../dates.ts";
+import { apiToBigInt, apiToSmallInt } from "../../inthelpers.ts";
 import {
   jCheckArray,
   jCheckBoolean,
@@ -14,12 +14,12 @@ import {
   jCheckObject,
   jCheckSet,
   jCheckString,
-} from "../../jsonchecks";
-import { SubscriptionEvent } from "../../rpcclients";
-import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types";
-import { dictionaryToStringMap, may } from "../encodings";
-import { hashTx } from "../hasher";
-import * as responses from "../responses";
+} from "../../jsonchecks.ts";
+import { SubscriptionEvent } from "../../rpcclients/index.ts";
+import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types.ts";
+import { dictionaryToStringMap, may } from "../encodings.ts";
+import { hashTx } from "../hasher.ts";
+import * as responses from "../responses.ts";
 
 interface AbciInfoResult {
   readonly response: RpcAbciInfoResponse;
diff --git a/packages/tendermint-rpc/src/comet1/comet1client.spec.ts b/packages/tendermint-rpc/src/comet1/comet1client.spec.ts
index e726e066d1..cb780c9a2d 100644
--- a/packages/tendermint-rpc/src/comet1/comet1client.spec.ts
+++ b/packages/tendermint-rpc/src/comet1/comet1client.spec.ts
@@ -4,7 +4,7 @@ import { assert, sleep } from "@cosmjs/utils";
 import { ReadonlyDate } from "readonly-date";
 import { Stream } from "xstream";
 
-import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients";
+import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients/index.ts";
 import {
   buildKvTx,
   ExpectedValues,
@@ -13,11 +13,11 @@ import {
   tendermintEnabled,
   tendermintInstances,
   tendermintSearchIndexUpdated,
-} from "../testutil.spec";
-import { Comet1Client } from "./comet1client";
-import { hashTx } from "./hasher";
-import { buildQuery } from "./requests";
-import * as responses from "./responses";
+} from "../testutil.spec.ts";
+import { Comet1Client } from "./comet1client.ts";
+import { hashTx } from "./hasher.ts";
+import { buildQuery } from "./requests.ts";
+import * as responses from "./responses.ts";
 
 /**
  * Runs tests using given client. A compatible backend must be running for this suite.
diff --git a/packages/tendermint-rpc/src/comet1/comet1client.ts b/packages/tendermint-rpc/src/comet1/comet1client.ts
index d59f04ea67..eda6ba988b 100644
--- a/packages/tendermint-rpc/src/comet1/comet1client.ts
+++ b/packages/tendermint-rpc/src/comet1/comet1client.ts
@@ -8,10 +8,10 @@ import {
   RpcClient,
   SubscriptionEvent,
   WebsocketClient,
-} from "../rpcclients";
-import { Params, Responses } from "./adaptor";
-import * as requests from "./requests";
-import * as responses from "./responses";
+} from "../rpcclients/index.ts";
+import { Params, Responses } from "./adaptor/index.ts";
+import * as requests from "./requests.ts";
+import * as responses from "./responses.ts";
 
 // Encoder is a generic that matches all methods of Params
 type Encoder<T extends requests.Request> = (req: T) => JsonRpcRequest;
diff --git a/packages/tendermint-rpc/src/comet1/encodings.spec.ts b/packages/tendermint-rpc/src/comet1/encodings.spec.ts
index b4921d3b73..fa9075e798 100644
--- a/packages/tendermint-rpc/src/comet1/encodings.spec.ts
+++ b/packages/tendermint-rpc/src/comet1/encodings.spec.ts
@@ -7,7 +7,7 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
+} from "./encodings.ts";
 
 describe("encodings", () => {
   describe("encodeString", () => {
diff --git a/packages/tendermint-rpc/src/comet1/encodings.ts b/packages/tendermint-rpc/src/comet1/encodings.ts
index 5d5dd8e6f3..8cc4c6243a 100644
--- a/packages/tendermint-rpc/src/comet1/encodings.ts
+++ b/packages/tendermint-rpc/src/comet1/encodings.ts
@@ -1,7 +1,7 @@
 import { toUtf8 } from "@cosmjs/encoding";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { BlockId, Version } from "./responses";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { BlockId, Version } from "./responses.ts";
 
 // may will run the transform if value is defined, otherwise returns undefined
 export function may<T, U>(transform: (val: T) => U, value: T | null | undefined): U | undefined {
diff --git a/packages/tendermint-rpc/src/comet1/hasher.spec.ts b/packages/tendermint-rpc/src/comet1/hasher.spec.ts
index c66448757c..c6c223766d 100644
--- a/packages/tendermint-rpc/src/comet1/hasher.spec.ts
+++ b/packages/tendermint-rpc/src/comet1/hasher.spec.ts
@@ -1,8 +1,8 @@
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { hashBlock, hashTx } from "./hasher";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { hashBlock, hashTx } from "./hasher.ts";
 
 describe("Hasher", () => {
   it("creates transaction hash equal to local test", () => {
diff --git a/packages/tendermint-rpc/src/comet1/hasher.ts b/packages/tendermint-rpc/src/comet1/hasher.ts
index 036f10728e..00aabc0d1d 100644
--- a/packages/tendermint-rpc/src/comet1/hasher.ts
+++ b/packages/tendermint-rpc/src/comet1/hasher.ts
@@ -7,8 +7,8 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
-import { Header } from "./responses";
+} from "./encodings.ts";
+import { Header } from "./responses.ts";
 
 // hash is sha256
 // https://github.com/tendermint/tendermint/blob/master/UPGRADING.md#v0260
diff --git a/packages/tendermint-rpc/src/comet1/index.ts b/packages/tendermint-rpc/src/comet1/index.ts
index c613057185..a1c6ff5e94 100644
--- a/packages/tendermint-rpc/src/comet1/index.ts
+++ b/packages/tendermint-rpc/src/comet1/index.ts
@@ -1,7 +1,7 @@
 // Note: all exports in this module are publicly available via
 // `import { comet1 } from "@cosmjs/tendermint-rpc"`
 
-export { Comet1Client } from "./comet1client";
+export { Comet1Client } from "./comet1client.ts";
 export type {
   AbciInfoRequest,
   AbciQueryParams,
@@ -26,8 +26,8 @@ export type {
   TxSearchRequest,
   ValidatorsParams,
   ValidatorsRequest,
-} from "./requests";
-export { Method, SubscriptionEventType } from "./requests";
+} from "./requests.ts";
+export { Method, SubscriptionEventType } from "./requests.ts";
 export type {
   AbciInfoResponse,
   AbciQueryResponse,
@@ -73,5 +73,5 @@ export type {
   ValidatorsResponse,
   Version,
   Vote,
-} from "./responses";
-export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses";
+} from "./responses.ts";
+export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses.ts";
diff --git a/packages/tendermint-rpc/src/comet1/requests.spec.ts b/packages/tendermint-rpc/src/comet1/requests.spec.ts
index f2134ea8d6..019ce06984 100644
--- a/packages/tendermint-rpc/src/comet1/requests.spec.ts
+++ b/packages/tendermint-rpc/src/comet1/requests.spec.ts
@@ -1,4 +1,4 @@
-import { buildQuery } from "./requests";
+import { buildQuery } from "./requests.ts";
 
 describe("Requests", () => {
   describe("buildQuery", () => {
diff --git a/packages/tendermint-rpc/src/comet1/responses.ts b/packages/tendermint-rpc/src/comet1/responses.ts
index ef49f049d6..cb99856e0a 100644
--- a/packages/tendermint-rpc/src/comet1/responses.ts
+++ b/packages/tendermint-rpc/src/comet1/responses.ts
@@ -1,7 +1,7 @@
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { CommitSignature, ValidatorPubkey } from "../types";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { CommitSignature, ValidatorPubkey } from "../types.ts";
 
 export type Response =
   | AbciInfoResponse
diff --git a/packages/tendermint-rpc/src/comet38/adaptor/index.ts b/packages/tendermint-rpc/src/comet38/adaptor/index.ts
index 38e924802f..687e85be3a 100644
--- a/packages/tendermint-rpc/src/comet38/adaptor/index.ts
+++ b/packages/tendermint-rpc/src/comet38/adaptor/index.ts
@@ -1,2 +1,2 @@
-export { Params } from "./requests";
-export { Responses } from "./responses";
+export { Params } from "./requests.ts";
+export { Responses } from "./responses.ts";
diff --git a/packages/tendermint-rpc/src/comet38/adaptor/requests.ts b/packages/tendermint-rpc/src/comet38/adaptor/requests.ts
index 2b5f483a29..34d833c262 100644
--- a/packages/tendermint-rpc/src/comet38/adaptor/requests.ts
+++ b/packages/tendermint-rpc/src/comet38/adaptor/requests.ts
@@ -2,11 +2,11 @@
 import { toBase64, toHex } from "@cosmjs/encoding";
 import { JsonRpcRequest } from "@cosmjs/json-rpc";
 
-import { smallIntToApi } from "../../inthelpers";
-import { jCheckNonEmptyString } from "../../jsonchecks";
-import { createJsonRpcRequest } from "../../jsonrpc";
-import { may } from "../encodings";
-import * as requests from "../requests";
+import { smallIntToApi } from "../../inthelpers.ts";
+import { jCheckNonEmptyString } from "../../jsonchecks.ts";
+import { createJsonRpcRequest } from "../../jsonrpc.ts";
+import { may } from "../encodings.ts";
+import * as requests from "../requests.ts";
 
 interface HeightParam {
   readonly height?: number;
diff --git a/packages/tendermint-rpc/src/comet38/adaptor/responses.spec.ts b/packages/tendermint-rpc/src/comet38/adaptor/responses.spec.ts
index 3f06df8ec1..3c105f0356 100644
--- a/packages/tendermint-rpc/src/comet38/adaptor/responses.spec.ts
+++ b/packages/tendermint-rpc/src/comet38/adaptor/responses.spec.ts
@@ -6,7 +6,7 @@ import {
   decodeValidatorGenesis,
   decodeValidatorInfo,
   decodeValidatorUpdate,
-} from "./responses";
+} from "./responses.ts";
 
 describe("Responses", () => {
   describe("decodeEvent", () => {
diff --git a/packages/tendermint-rpc/src/comet38/adaptor/responses.ts b/packages/tendermint-rpc/src/comet38/adaptor/responses.ts
index a361cfb190..00efd2ea26 100644
--- a/packages/tendermint-rpc/src/comet38/adaptor/responses.ts
+++ b/packages/tendermint-rpc/src/comet38/adaptor/responses.ts
@@ -3,8 +3,8 @@ import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { JsonRpcSuccessResponse } from "@cosmjs/json-rpc";
 import { assert } from "@cosmjs/utils";
 
-import { fromRfc3339WithNanoseconds } from "../../dates";
-import { apiToBigInt, apiToSmallInt } from "../../inthelpers";
+import { fromRfc3339WithNanoseconds } from "../../dates.ts";
+import { apiToBigInt, apiToSmallInt } from "../../inthelpers.ts";
 import {
   jCheckArray,
   jCheckBoolean,
@@ -14,12 +14,12 @@ import {
   jCheckObject,
   jCheckSet,
   jCheckString,
-} from "../../jsonchecks";
-import { SubscriptionEvent } from "../../rpcclients";
-import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types";
-import { dictionaryToStringMap, may } from "../encodings";
-import { hashTx } from "../hasher";
-import * as responses from "../responses";
+} from "../../jsonchecks.ts";
+import { SubscriptionEvent } from "../../rpcclients/index.ts";
+import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types.ts";
+import { dictionaryToStringMap, may } from "../encodings.ts";
+import { hashTx } from "../hasher.ts";
+import * as responses from "../responses.ts";
 
 interface AbciInfoResult {
   readonly response: RpcAbciInfoResponse;
diff --git a/packages/tendermint-rpc/src/comet38/comet38client.spec.ts b/packages/tendermint-rpc/src/comet38/comet38client.spec.ts
index 91f85a1dac..d6ae06fa7d 100644
--- a/packages/tendermint-rpc/src/comet38/comet38client.spec.ts
+++ b/packages/tendermint-rpc/src/comet38/comet38client.spec.ts
@@ -4,7 +4,7 @@ import { assert, sleep } from "@cosmjs/utils";
 import { ReadonlyDate } from "readonly-date";
 import { Stream } from "xstream";
 
-import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients";
+import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients/index.ts";
 import {
   buildKvTx,
   ExpectedValues,
@@ -13,11 +13,11 @@ import {
   tendermintEnabled,
   tendermintInstances,
   tendermintSearchIndexUpdated,
-} from "../testutil.spec";
-import { Comet38Client } from "./comet38client";
-import { hashTx } from "./hasher";
-import { buildQuery } from "./requests";
-import * as responses from "./responses";
+} from "../testutil.spec.ts";
+import { Comet38Client } from "./comet38client.ts";
+import { hashTx } from "./hasher.ts";
+import { buildQuery } from "./requests.ts";
+import * as responses from "./responses.ts";
 
 /**
  * Runs tests using given client. A compatible backend must be running for this suite.
diff --git a/packages/tendermint-rpc/src/comet38/comet38client.ts b/packages/tendermint-rpc/src/comet38/comet38client.ts
index af6901bac0..43de5c1665 100644
--- a/packages/tendermint-rpc/src/comet38/comet38client.ts
+++ b/packages/tendermint-rpc/src/comet38/comet38client.ts
@@ -8,10 +8,10 @@ import {
   RpcClient,
   SubscriptionEvent,
   WebsocketClient,
-} from "../rpcclients";
-import { Params, Responses } from "./adaptor";
-import * as requests from "./requests";
-import * as responses from "./responses";
+} from "../rpcclients/index.ts";
+import { Params, Responses } from "./adaptor/index.ts";
+import * as requests from "./requests.ts";
+import * as responses from "./responses.ts";
 
 // Encoder is a generic that matches all methods of Params
 type Encoder<T extends requests.Request> = (req: T) => JsonRpcRequest;
diff --git a/packages/tendermint-rpc/src/comet38/encodings.spec.ts b/packages/tendermint-rpc/src/comet38/encodings.spec.ts
index b4921d3b73..fa9075e798 100644
--- a/packages/tendermint-rpc/src/comet38/encodings.spec.ts
+++ b/packages/tendermint-rpc/src/comet38/encodings.spec.ts
@@ -7,7 +7,7 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
+} from "./encodings.ts";
 
 describe("encodings", () => {
   describe("encodeString", () => {
diff --git a/packages/tendermint-rpc/src/comet38/encodings.ts b/packages/tendermint-rpc/src/comet38/encodings.ts
index 5d5dd8e6f3..8cc4c6243a 100644
--- a/packages/tendermint-rpc/src/comet38/encodings.ts
+++ b/packages/tendermint-rpc/src/comet38/encodings.ts
@@ -1,7 +1,7 @@
 import { toUtf8 } from "@cosmjs/encoding";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { BlockId, Version } from "./responses";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { BlockId, Version } from "./responses.ts";
 
 // may will run the transform if value is defined, otherwise returns undefined
 export function may<T, U>(transform: (val: T) => U, value: T | null | undefined): U | undefined {
diff --git a/packages/tendermint-rpc/src/comet38/hasher.spec.ts b/packages/tendermint-rpc/src/comet38/hasher.spec.ts
index c66448757c..c6c223766d 100644
--- a/packages/tendermint-rpc/src/comet38/hasher.spec.ts
+++ b/packages/tendermint-rpc/src/comet38/hasher.spec.ts
@@ -1,8 +1,8 @@
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { hashBlock, hashTx } from "./hasher";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { hashBlock, hashTx } from "./hasher.ts";
 
 describe("Hasher", () => {
   it("creates transaction hash equal to local test", () => {
diff --git a/packages/tendermint-rpc/src/comet38/hasher.ts b/packages/tendermint-rpc/src/comet38/hasher.ts
index 036f10728e..00aabc0d1d 100644
--- a/packages/tendermint-rpc/src/comet38/hasher.ts
+++ b/packages/tendermint-rpc/src/comet38/hasher.ts
@@ -7,8 +7,8 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
-import { Header } from "./responses";
+} from "./encodings.ts";
+import { Header } from "./responses.ts";
 
 // hash is sha256
 // https://github.com/tendermint/tendermint/blob/master/UPGRADING.md#v0260
diff --git a/packages/tendermint-rpc/src/comet38/index.ts b/packages/tendermint-rpc/src/comet38/index.ts
index 28b5fde55b..1e6ea9ec57 100644
--- a/packages/tendermint-rpc/src/comet38/index.ts
+++ b/packages/tendermint-rpc/src/comet38/index.ts
@@ -1,7 +1,7 @@
 // Note: all exports in this module are publicly available via
 // `import { comet38 } from "@cosmjs/tendermint-rpc"`
 
-export { Comet38Client } from "./comet38client";
+export { Comet38Client } from "./comet38client.ts";
 export type {
   AbciInfoRequest,
   AbciQueryParams,
@@ -26,8 +26,8 @@ export type {
   TxSearchRequest,
   ValidatorsParams,
   ValidatorsRequest,
-} from "./requests";
-export { Method, SubscriptionEventType } from "./requests";
+} from "./requests.ts";
+export { Method, SubscriptionEventType } from "./requests.ts";
 export type {
   AbciInfoResponse,
   AbciQueryResponse,
@@ -72,5 +72,5 @@ export type {
   ValidatorsResponse,
   Version,
   Vote,
-} from "./responses";
-export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses";
+} from "./responses.ts";
+export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses.ts";
diff --git a/packages/tendermint-rpc/src/comet38/requests.spec.ts b/packages/tendermint-rpc/src/comet38/requests.spec.ts
index f2134ea8d6..019ce06984 100644
--- a/packages/tendermint-rpc/src/comet38/requests.spec.ts
+++ b/packages/tendermint-rpc/src/comet38/requests.spec.ts
@@ -1,4 +1,4 @@
-import { buildQuery } from "./requests";
+import { buildQuery } from "./requests.ts";
 
 describe("Requests", () => {
   describe("buildQuery", () => {
diff --git a/packages/tendermint-rpc/src/comet38/responses.ts b/packages/tendermint-rpc/src/comet38/responses.ts
index 492dfcb3f2..babbab4ce3 100644
--- a/packages/tendermint-rpc/src/comet38/responses.ts
+++ b/packages/tendermint-rpc/src/comet38/responses.ts
@@ -1,7 +1,7 @@
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { CommitSignature, ValidatorPubkey } from "../types";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { CommitSignature, ValidatorPubkey } from "../types.ts";
 
 export type Response =
   | AbciInfoResponse
diff --git a/packages/tendermint-rpc/src/dates.spec.ts b/packages/tendermint-rpc/src/dates.spec.ts
index 25862012d8..36fdc9548e 100644
--- a/packages/tendermint-rpc/src/dates.spec.ts
+++ b/packages/tendermint-rpc/src/dates.spec.ts
@@ -7,7 +7,7 @@ import {
   fromSeconds,
   toRfc3339WithNanoseconds,
   toSeconds,
-} from "./dates";
+} from "./dates.ts";
 
 describe("dates", () => {
   describe("fromRfc3339WithNanoseconds", () => {
diff --git a/packages/tendermint-rpc/src/index.ts b/packages/tendermint-rpc/src/index.ts
index c71515d692..52bc21b20f 100644
--- a/packages/tendermint-rpc/src/index.ts
+++ b/packages/tendermint-rpc/src/index.ts
@@ -3,11 +3,11 @@ export {
   pubkeyToRawAddress,
   rawEd25519PubkeyToRawAddress,
   rawSecp256k1PubkeyToRawAddress,
-} from "./addresses";
-export * as comet1 from "./comet1";
-export { Comet1Client } from "./comet1";
-export * as comet38 from "./comet38";
-export { Comet38Client } from "./comet38";
+} from "./addresses.ts";
+export * as comet1 from "./comet1/index.ts";
+export { Comet1Client } from "./comet1/index.ts";
+export * as comet38 from "./comet38/index.ts";
+export { Comet38Client } from "./comet38/index.ts";
 export {
   type ReadonlyDateWithNanoseconds,
   DateTime,
@@ -15,20 +15,20 @@ export {
   fromSeconds,
   toRfc3339WithNanoseconds,
   toSeconds,
-} from "./dates";
+} from "./dates.ts";
 // The public Comet37Client/Comet38Client/Comet1Client.create constructor allows manually choosing an RpcClient.
 // This is currently the only way to switch to the HttpBatchClient (which may become default at some point).
 // Due to this API, we make RPC client implementations public.
-export type { HttpBatchClientOptions, HttpEndpoint, RpcClient } from "./rpcclients";
-export { HttpBatchClient, HttpClient, WebsocketClient } from "./rpcclients";
-export * as tendermint37 from "./tendermint37";
-export { Tendermint37Client } from "./tendermint37";
-export type { CometClient } from "./tendermintclient";
-export { connectComet, isComet1Client, isComet38Client, isTendermint37Client } from "./tendermintclient";
+export type { HttpBatchClientOptions, HttpEndpoint, RpcClient } from "./rpcclients/index.ts";
+export { HttpBatchClient, HttpClient, WebsocketClient } from "./rpcclients/index.ts";
+export * as tendermint37 from "./tendermint37/index.ts";
+export { Tendermint37Client } from "./tendermint37/index.ts";
+export type { CometClient } from "./tendermintclient.ts";
+export { connectComet, isComet1Client, isComet38Client, isTendermint37Client } from "./tendermintclient.ts";
 export type {
   CommitSignature,
   ValidatorEd25519Pubkey,
   ValidatorPubkey,
   ValidatorSecp256k1Pubkey,
-} from "./types";
-export { BlockIdFlag } from "./types";
+} from "./types.ts";
+export { BlockIdFlag } from "./types.ts";
diff --git a/packages/tendermint-rpc/src/inthelpers.spec.ts b/packages/tendermint-rpc/src/inthelpers.spec.ts
index 3c2a065e94..e12be3d474 100644
--- a/packages/tendermint-rpc/src/inthelpers.spec.ts
+++ b/packages/tendermint-rpc/src/inthelpers.spec.ts
@@ -1,4 +1,4 @@
-import { apiToBigInt } from "./inthelpers";
+import { apiToBigInt } from "./inthelpers.ts";
 
 describe("inthelpers", () => {
   describe("apiToBigInt", () => {
diff --git a/packages/tendermint-rpc/src/inthelpers.ts b/packages/tendermint-rpc/src/inthelpers.ts
index 109e36a585..4a29e75c62 100644
--- a/packages/tendermint-rpc/src/inthelpers.ts
+++ b/packages/tendermint-rpc/src/inthelpers.ts
@@ -1,6 +1,6 @@
 import { Int53 } from "@cosmjs/math";
 
-import { jCheckString } from "./jsonchecks";
+import { jCheckString } from "./jsonchecks.ts";
 
 /**
  * Takes an integer value from the Tendermint RPC API and
diff --git a/packages/tendermint-rpc/src/jsonchecks.spec.ts b/packages/tendermint-rpc/src/jsonchecks.spec.ts
index a63d26d257..52daff2055 100644
--- a/packages/tendermint-rpc/src/jsonchecks.spec.ts
+++ b/packages/tendermint-rpc/src/jsonchecks.spec.ts
@@ -1,6 +1,6 @@
 import { fromHex } from "@cosmjs/encoding";
 
-import { jCheckNonEmptyString, jCheckNonZeroNumber } from "./jsonchecks";
+import { jCheckNonEmptyString, jCheckNonZeroNumber } from "./jsonchecks.ts";
 
 describe("jCheckNonEmptyString", () => {
   it("throws for wrong input type", () => {
diff --git a/packages/tendermint-rpc/src/jsonrpc.spec.ts b/packages/tendermint-rpc/src/jsonrpc.spec.ts
index 2f86a235b1..0298eef6d6 100644
--- a/packages/tendermint-rpc/src/jsonrpc.spec.ts
+++ b/packages/tendermint-rpc/src/jsonrpc.spec.ts
@@ -1,4 +1,4 @@
-import { createJsonRpcRequest } from "./jsonrpc";
+import { createJsonRpcRequest } from "./jsonrpc.ts";
 
 describe("jsonrpc", () => {
   describe("createJsonRpcRequest", () => {
diff --git a/packages/tendermint-rpc/src/rpcclients/http.spec.ts b/packages/tendermint-rpc/src/rpcclients/http.spec.ts
index 68790dcf2b..7ef914fb9b 100644
--- a/packages/tendermint-rpc/src/rpcclients/http.spec.ts
+++ b/packages/tendermint-rpc/src/rpcclients/http.spec.ts
@@ -1,6 +1,6 @@
-import { createJsonRpcRequest } from "../jsonrpc";
-import { defaultInstance, tendermintEnabled } from "../testutil.spec";
-import { http } from "./http";
+import { createJsonRpcRequest } from "../jsonrpc.ts";
+import { defaultInstance, tendermintEnabled } from "../testutil.spec.ts";
+import { http } from "./http.ts";
 
 const httpServerEnabled = !!globalThis.process?.env.HTTPSERVER_ENABLED;
 
diff --git a/packages/tendermint-rpc/src/rpcclients/httpbatchclient.spec.ts b/packages/tendermint-rpc/src/rpcclients/httpbatchclient.spec.ts
index dc184ea881..5b8278a905 100644
--- a/packages/tendermint-rpc/src/rpcclients/httpbatchclient.spec.ts
+++ b/packages/tendermint-rpc/src/rpcclients/httpbatchclient.spec.ts
@@ -1,6 +1,6 @@
-import { createJsonRpcRequest } from "../jsonrpc";
-import { defaultInstance, tendermintEnabled } from "../testutil.spec";
-import { HttpBatchClient } from "./httpbatchclient";
+import { createJsonRpcRequest } from "../jsonrpc.ts";
+import { defaultInstance, tendermintEnabled } from "../testutil.spec.ts";
+import { HttpBatchClient } from "./httpbatchclient.ts";
 
 (tendermintEnabled ? describe : xdescribe)("HttpBatchClient", () => {
   const tendermintUrl = "http://" + defaultInstance.url;
diff --git a/packages/tendermint-rpc/src/rpcclients/httpbatchclient.ts b/packages/tendermint-rpc/src/rpcclients/httpbatchclient.ts
index 63d8a93818..29050bc37f 100644
--- a/packages/tendermint-rpc/src/rpcclients/httpbatchclient.ts
+++ b/packages/tendermint-rpc/src/rpcclients/httpbatchclient.ts
@@ -5,9 +5,9 @@ import {
   parseJsonRpcResponse,
 } from "@cosmjs/json-rpc";
 
-import { http } from "./http";
-import { HttpEndpoint } from "./httpclient";
-import { hasProtocol, RpcClient } from "./rpcclient";
+import { http } from "./http.ts";
+import { HttpEndpoint } from "./httpclient.ts";
+import { hasProtocol, RpcClient } from "./rpcclient.ts";
 
 export interface HttpBatchClientOptions {
   /** Interval for dispatching batches (in milliseconds) */
diff --git a/packages/tendermint-rpc/src/rpcclients/httpclient.spec.ts b/packages/tendermint-rpc/src/rpcclients/httpclient.spec.ts
index 0080ec0f35..f75ee68dee 100644
--- a/packages/tendermint-rpc/src/rpcclients/httpclient.spec.ts
+++ b/packages/tendermint-rpc/src/rpcclients/httpclient.spec.ts
@@ -1,6 +1,6 @@
-import { createJsonRpcRequest } from "../jsonrpc";
-import { defaultInstance, tendermintEnabled } from "../testutil.spec";
-import { HttpClient } from "./httpclient";
+import { createJsonRpcRequest } from "../jsonrpc.ts";
+import { defaultInstance, tendermintEnabled } from "../testutil.spec.ts";
+import { HttpClient } from "./httpclient.ts";
 
 (tendermintEnabled ? describe : xdescribe)("HttpClient", () => {
   const tendermintUrl = "http://" + defaultInstance.url;
diff --git a/packages/tendermint-rpc/src/rpcclients/httpclient.ts b/packages/tendermint-rpc/src/rpcclients/httpclient.ts
index 17ef3e1303..ec0145763a 100644
--- a/packages/tendermint-rpc/src/rpcclients/httpclient.ts
+++ b/packages/tendermint-rpc/src/rpcclients/httpclient.ts
@@ -5,8 +5,8 @@ import {
   parseJsonRpcResponse,
 } from "@cosmjs/json-rpc";
 
-import { http } from "./http";
-import { hasProtocol, RpcClient } from "./rpcclient";
+import { http } from "./http.ts";
+import { hasProtocol, RpcClient } from "./rpcclient.ts";
 
 export interface HttpEndpoint {
   /**
diff --git a/packages/tendermint-rpc/src/rpcclients/index.ts b/packages/tendermint-rpc/src/rpcclients/index.ts
index e267734e59..6b3500c542 100644
--- a/packages/tendermint-rpc/src/rpcclients/index.ts
+++ b/packages/tendermint-rpc/src/rpcclients/index.ts
@@ -1,7 +1,7 @@
 // This folder contains Tendermint-specific RPC clients
 
-export { type HttpBatchClientOptions, HttpBatchClient } from "./httpbatchclient";
-export { type HttpEndpoint, HttpClient } from "./httpclient";
-export type { RpcClient, RpcStreamingClient, SubscriptionEvent } from "./rpcclient";
-export { instanceOfRpcStreamingClient } from "./rpcclient";
-export { WebsocketClient } from "./websocketclient";
+export { type HttpBatchClientOptions, HttpBatchClient } from "./httpbatchclient.ts";
+export { type HttpEndpoint, HttpClient } from "./httpclient.ts";
+export type { RpcClient, RpcStreamingClient, SubscriptionEvent } from "./rpcclient.ts";
+export { instanceOfRpcStreamingClient } from "./rpcclient.ts";
+export { WebsocketClient } from "./websocketclient.ts";
diff --git a/packages/tendermint-rpc/src/rpcclients/rpcclient.spec.ts b/packages/tendermint-rpc/src/rpcclients/rpcclient.spec.ts
index 37262534cb..bd32b996e2 100644
--- a/packages/tendermint-rpc/src/rpcclients/rpcclient.spec.ts
+++ b/packages/tendermint-rpc/src/rpcclients/rpcclient.spec.ts
@@ -1,8 +1,8 @@
-import { createJsonRpcRequest } from "../jsonrpc";
-import { defaultInstance, tendermintEnabled } from "../testutil.spec";
-import { HttpClient } from "./httpclient";
-import { hasProtocol, instanceOfRpcStreamingClient } from "./rpcclient";
-import { WebsocketClient } from "./websocketclient";
+import { createJsonRpcRequest } from "../jsonrpc.ts";
+import { defaultInstance, tendermintEnabled } from "../testutil.spec.ts";
+import { HttpClient } from "./httpclient.ts";
+import { hasProtocol, instanceOfRpcStreamingClient } from "./rpcclient.ts";
+import { WebsocketClient } from "./websocketclient.ts";
 
 (tendermintEnabled ? describe : xdescribe)("RpcClient", () => {
   const httpUrl = "http://" + defaultInstance.url;
diff --git a/packages/tendermint-rpc/src/rpcclients/websocketclient.spec.ts b/packages/tendermint-rpc/src/rpcclients/websocketclient.spec.ts
index 847cb86039..cbbfe8162b 100644
--- a/packages/tendermint-rpc/src/rpcclients/websocketclient.spec.ts
+++ b/packages/tendermint-rpc/src/rpcclients/websocketclient.spec.ts
@@ -2,10 +2,10 @@ import { Uint53 } from "@cosmjs/math";
 import { toListPromise } from "@cosmjs/stream";
 import { Stream } from "xstream";
 
-import { createJsonRpcRequest } from "../jsonrpc";
-import { defaultInstance, tendermintEnabled } from "../testutil.spec";
-import { SubscriptionEvent } from "./rpcclient";
-import { WebsocketClient } from "./websocketclient";
+import { createJsonRpcRequest } from "../jsonrpc.ts";
+import { defaultInstance, tendermintEnabled } from "../testutil.spec.ts";
+import { SubscriptionEvent } from "./rpcclient.ts";
+import { WebsocketClient } from "./websocketclient.ts";
 
 (tendermintEnabled ? describe : xdescribe)("WebsocketClient", () => {
   const { blockTime, url } = defaultInstance;
diff --git a/packages/tendermint-rpc/src/rpcclients/websocketclient.ts b/packages/tendermint-rpc/src/rpcclients/websocketclient.ts
index 51708a43ed..29a1fe7a89 100644
--- a/packages/tendermint-rpc/src/rpcclients/websocketclient.ts
+++ b/packages/tendermint-rpc/src/rpcclients/websocketclient.ts
@@ -10,7 +10,7 @@ import { ConnectionStatus, ReconnectingSocket, SocketWrapperMessageEvent } from
 import { firstEvent } from "@cosmjs/stream";
 import { Listener, Producer, Stream, Subscription } from "xstream";
 
-import { hasProtocol, RpcStreamingClient, SubscriptionEvent } from "./rpcclient";
+import { hasProtocol, RpcStreamingClient, SubscriptionEvent } from "./rpcclient.ts";
 
 function defaultErrorHandler(error: any): never {
   throw error;
diff --git a/packages/tendermint-rpc/src/tendermint37/adaptor/index.ts b/packages/tendermint-rpc/src/tendermint37/adaptor/index.ts
index 38e924802f..687e85be3a 100644
--- a/packages/tendermint-rpc/src/tendermint37/adaptor/index.ts
+++ b/packages/tendermint-rpc/src/tendermint37/adaptor/index.ts
@@ -1,2 +1,2 @@
-export { Params } from "./requests";
-export { Responses } from "./responses";
+export { Params } from "./requests.ts";
+export { Responses } from "./responses.ts";
diff --git a/packages/tendermint-rpc/src/tendermint37/adaptor/requests.ts b/packages/tendermint-rpc/src/tendermint37/adaptor/requests.ts
index c2ece2617e..229a92c39d 100644
--- a/packages/tendermint-rpc/src/tendermint37/adaptor/requests.ts
+++ b/packages/tendermint-rpc/src/tendermint37/adaptor/requests.ts
@@ -2,10 +2,10 @@
 import { toBase64, toHex } from "@cosmjs/encoding";
 import { JsonRpcRequest } from "@cosmjs/json-rpc";
 
-import { smallIntToApi } from "../../inthelpers";
-import { createJsonRpcRequest } from "../../jsonrpc";
-import { may } from "../encodings";
-import * as requests from "../requests";
+import { smallIntToApi } from "../../inthelpers.ts";
+import { createJsonRpcRequest } from "../../jsonrpc.ts";
+import { may } from "../encodings.ts";
+import * as requests from "../requests.ts";
 
 interface HeightParam {
   readonly height?: number;
diff --git a/packages/tendermint-rpc/src/tendermint37/adaptor/responses.spec.ts b/packages/tendermint-rpc/src/tendermint37/adaptor/responses.spec.ts
index f50fe50b82..1e40086602 100644
--- a/packages/tendermint-rpc/src/tendermint37/adaptor/responses.spec.ts
+++ b/packages/tendermint-rpc/src/tendermint37/adaptor/responses.spec.ts
@@ -1,6 +1,11 @@
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 
-import { decodeEvent, decodeValidatorGenesis, decodeValidatorInfo, decodeValidatorUpdate } from "./responses";
+import {
+  decodeEvent,
+  decodeValidatorGenesis,
+  decodeValidatorInfo,
+  decodeValidatorUpdate,
+} from "./responses.ts";
 
 describe("Responses", () => {
   describe("decodeEvent", () => {
diff --git a/packages/tendermint-rpc/src/tendermint37/adaptor/responses.ts b/packages/tendermint-rpc/src/tendermint37/adaptor/responses.ts
index 9db5939a00..b8df029619 100644
--- a/packages/tendermint-rpc/src/tendermint37/adaptor/responses.ts
+++ b/packages/tendermint-rpc/src/tendermint37/adaptor/responses.ts
@@ -3,8 +3,8 @@ import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { JsonRpcSuccessResponse } from "@cosmjs/json-rpc";
 import { assert } from "@cosmjs/utils";
 
-import { fromRfc3339WithNanoseconds } from "../../dates";
-import { apiToBigInt, apiToSmallInt } from "../../inthelpers";
+import { fromRfc3339WithNanoseconds } from "../../dates.ts";
+import { apiToBigInt, apiToSmallInt } from "../../inthelpers.ts";
 import {
   jCheckArray,
   jCheckBoolean,
@@ -14,12 +14,12 @@ import {
   jCheckObject,
   jCheckSet,
   jCheckString,
-} from "../../jsonchecks";
-import { SubscriptionEvent } from "../../rpcclients";
-import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types";
-import { dictionaryToStringMap, may } from "../encodings";
-import { hashTx } from "../hasher";
-import * as responses from "../responses";
+} from "../../jsonchecks.ts";
+import { SubscriptionEvent } from "../../rpcclients/index.ts";
+import { BlockIdFlag, CommitSignature, ValidatorPubkey } from "../../types.ts";
+import { dictionaryToStringMap, may } from "../encodings.ts";
+import { hashTx } from "../hasher.ts";
+import * as responses from "../responses.ts";
 
 interface AbciInfoResult {
   readonly response: RpcAbciInfoResponse;
diff --git a/packages/tendermint-rpc/src/tendermint37/encodings.spec.ts b/packages/tendermint-rpc/src/tendermint37/encodings.spec.ts
index b4921d3b73..fa9075e798 100644
--- a/packages/tendermint-rpc/src/tendermint37/encodings.spec.ts
+++ b/packages/tendermint-rpc/src/tendermint37/encodings.spec.ts
@@ -7,7 +7,7 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
+} from "./encodings.ts";
 
 describe("encodings", () => {
   describe("encodeString", () => {
diff --git a/packages/tendermint-rpc/src/tendermint37/encodings.ts b/packages/tendermint-rpc/src/tendermint37/encodings.ts
index 5d5dd8e6f3..8cc4c6243a 100644
--- a/packages/tendermint-rpc/src/tendermint37/encodings.ts
+++ b/packages/tendermint-rpc/src/tendermint37/encodings.ts
@@ -1,7 +1,7 @@
 import { toUtf8 } from "@cosmjs/encoding";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { BlockId, Version } from "./responses";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { BlockId, Version } from "./responses.ts";
 
 // may will run the transform if value is defined, otherwise returns undefined
 export function may<T, U>(transform: (val: T) => U, value: T | null | undefined): U | undefined {
diff --git a/packages/tendermint-rpc/src/tendermint37/hasher.spec.ts b/packages/tendermint-rpc/src/tendermint37/hasher.spec.ts
index c66448757c..c6c223766d 100644
--- a/packages/tendermint-rpc/src/tendermint37/hasher.spec.ts
+++ b/packages/tendermint-rpc/src/tendermint37/hasher.spec.ts
@@ -1,8 +1,8 @@
 import { fromBase64, fromHex } from "@cosmjs/encoding";
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { hashBlock, hashTx } from "./hasher";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { hashBlock, hashTx } from "./hasher.ts";
 
 describe("Hasher", () => {
   it("creates transaction hash equal to local test", () => {
diff --git a/packages/tendermint-rpc/src/tendermint37/hasher.ts b/packages/tendermint-rpc/src/tendermint37/hasher.ts
index 036f10728e..00aabc0d1d 100644
--- a/packages/tendermint-rpc/src/tendermint37/hasher.ts
+++ b/packages/tendermint-rpc/src/tendermint37/hasher.ts
@@ -7,8 +7,8 @@ import {
   encodeTime,
   encodeUvarint,
   encodeVersion,
-} from "./encodings";
-import { Header } from "./responses";
+} from "./encodings.ts";
+import { Header } from "./responses.ts";
 
 // hash is sha256
 // https://github.com/tendermint/tendermint/blob/master/UPGRADING.md#v0260
diff --git a/packages/tendermint-rpc/src/tendermint37/index.ts b/packages/tendermint-rpc/src/tendermint37/index.ts
index fb2dbfd4d2..66233b2964 100644
--- a/packages/tendermint-rpc/src/tendermint37/index.ts
+++ b/packages/tendermint-rpc/src/tendermint37/index.ts
@@ -25,8 +25,8 @@ export type {
   TxSearchRequest,
   ValidatorsParams,
   ValidatorsRequest,
-} from "./requests";
-export { Method, SubscriptionEventType } from "./requests";
+} from "./requests.ts";
+export { Method, SubscriptionEventType } from "./requests.ts";
 export type {
   AbciInfoResponse,
   AbciQueryResponse,
@@ -71,6 +71,6 @@ export type {
   ValidatorsResponse,
   Version,
   Vote,
-} from "./responses";
-export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses";
-export { Tendermint37Client } from "./tendermint37client";
+} from "./responses.ts";
+export { broadcastTxCommitSuccess, broadcastTxSyncSuccess, VoteType } from "./responses.ts";
+export { Tendermint37Client } from "./tendermint37client.ts";
diff --git a/packages/tendermint-rpc/src/tendermint37/requests.spec.ts b/packages/tendermint-rpc/src/tendermint37/requests.spec.ts
index f2134ea8d6..019ce06984 100644
--- a/packages/tendermint-rpc/src/tendermint37/requests.spec.ts
+++ b/packages/tendermint-rpc/src/tendermint37/requests.spec.ts
@@ -1,4 +1,4 @@
-import { buildQuery } from "./requests";
+import { buildQuery } from "./requests.ts";
 
 describe("Requests", () => {
   describe("buildQuery", () => {
diff --git a/packages/tendermint-rpc/src/tendermint37/responses.ts b/packages/tendermint-rpc/src/tendermint37/responses.ts
index f1376b7396..5461c5d4f0 100644
--- a/packages/tendermint-rpc/src/tendermint37/responses.ts
+++ b/packages/tendermint-rpc/src/tendermint37/responses.ts
@@ -1,7 +1,7 @@
 import { ReadonlyDate } from "readonly-date";
 
-import { ReadonlyDateWithNanoseconds } from "../dates";
-import { CommitSignature, ValidatorPubkey } from "../types";
+import { ReadonlyDateWithNanoseconds } from "../dates.ts";
+import { CommitSignature, ValidatorPubkey } from "../types.ts";
 
 export type Response =
   | AbciInfoResponse
diff --git a/packages/tendermint-rpc/src/tendermint37/tendermint37client.spec.ts b/packages/tendermint-rpc/src/tendermint37/tendermint37client.spec.ts
index 2abc88646e..85fb680503 100644
--- a/packages/tendermint-rpc/src/tendermint37/tendermint37client.spec.ts
+++ b/packages/tendermint-rpc/src/tendermint37/tendermint37client.spec.ts
@@ -4,7 +4,7 @@ import { assert, sleep } from "@cosmjs/utils";
 import { ReadonlyDate } from "readonly-date";
 import { Stream } from "xstream";
 
-import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients";
+import { HttpClient, RpcClient, WebsocketClient } from "../rpcclients/index.ts";
 import {
   buildKvTx,
   ExpectedValues,
@@ -13,11 +13,11 @@ import {
   tendermintEnabled,
   tendermintInstances,
   tendermintSearchIndexUpdated,
-} from "../testutil.spec";
-import { hashTx } from "./hasher";
-import { buildQuery } from "./requests";
-import * as responses from "./responses";
-import { Tendermint37Client } from "./tendermint37client";
+} from "../testutil.spec.ts";
+import { hashTx } from "./hasher.ts";
+import { buildQuery } from "./requests.ts";
+import * as responses from "./responses.ts";
+import { Tendermint37Client } from "./tendermint37client.ts";
 
 /**
  * Runs tests using given client. A compatible backend must be running for this suite.
diff --git a/packages/tendermint-rpc/src/tendermint37/tendermint37client.ts b/packages/tendermint-rpc/src/tendermint37/tendermint37client.ts
index 1b29f3a3ab..01a25a601c 100644
--- a/packages/tendermint-rpc/src/tendermint37/tendermint37client.ts
+++ b/packages/tendermint-rpc/src/tendermint37/tendermint37client.ts
@@ -8,10 +8,10 @@ import {
   RpcClient,
   SubscriptionEvent,
   WebsocketClient,
-} from "../rpcclients";
-import { Params, Responses } from "./adaptor";
-import * as requests from "./requests";
-import * as responses from "./responses";
+} from "../rpcclients/index.ts";
+import { Params, Responses } from "./adaptor/index.ts";
+import * as requests from "./requests.ts";
+import * as responses from "./responses.ts";
 
 // Encoder is a generic that matches all methods of Params
 type Encoder<T extends requests.Request> = (req: T) => JsonRpcRequest;
diff --git a/packages/tendermint-rpc/src/tendermintclient.ts b/packages/tendermint-rpc/src/tendermintclient.ts
index dfe6a50ed8..b4a3d6d900 100644
--- a/packages/tendermint-rpc/src/tendermintclient.ts
+++ b/packages/tendermint-rpc/src/tendermintclient.ts
@@ -1,7 +1,7 @@
-import { Comet1Client } from "./comet1";
-import { Comet38Client } from "./comet38";
-import { HttpEndpoint } from "./rpcclients";
-import { Tendermint37Client } from "./tendermint37";
+import { Comet1Client } from "./comet1/index.ts";
+import { Comet38Client } from "./comet38/index.ts";
+import { HttpEndpoint } from "./rpcclients/index.ts";
+import { Tendermint37Client } from "./tendermint37/index.ts";
 
 /** A CometClient is either a Tendermint37Client Comet38Client or a Comet1Client */
 export type CometClient = Tendermint37Client | Comet38Client | Comet1Client;
diff --git a/packages/tendermint-rpc/src/tendermintsclient.spec.ts b/packages/tendermint-rpc/src/tendermintsclient.spec.ts
index 2beddc59b0..0456d85a52 100644
--- a/packages/tendermint-rpc/src/tendermintsclient.spec.ts
+++ b/packages/tendermint-rpc/src/tendermintsclient.spec.ts
@@ -1,5 +1,5 @@
-import { connectComet, isComet1Client, isComet38Client, isTendermint37Client } from "./tendermintclient";
-import { tendermintEnabled, tendermintInstances } from "./testutil.spec";
+import { connectComet, isComet1Client, isComet38Client, isTendermint37Client } from "./tendermintclient.ts";
+import { tendermintEnabled, tendermintInstances } from "./testutil.spec.ts";
 
 (tendermintEnabled ? describe : xdescribe)("connectComet", () => {
   it("works for Tendermint 0.37", async () => {
diff --git a/packages/tendermint-rpc/src/types.ts b/packages/tendermint-rpc/src/types.ts
index 4c1b2ebc3a..a03494a8af 100644
--- a/packages/tendermint-rpc/src/types.ts
+++ b/packages/tendermint-rpc/src/types.ts
@@ -1,7 +1,7 @@
 // Types in this file are exported outside of the @cosmjs/tendermint-rpc package,
 // e.g. as part of a request or response
 
-import { ReadonlyDateWithNanoseconds } from "./dates";
+import { ReadonlyDateWithNanoseconds } from "./dates.ts";
 
 export interface ValidatorEd25519Pubkey {
   readonly algorithm: "ed25519";
diff --git a/packages/utils/src/array.spec.ts b/packages/utils/src/array.spec.ts
index 0dae826e19..a9ee463bcb 100644
--- a/packages/utils/src/array.spec.ts
+++ b/packages/utils/src/array.spec.ts
@@ -1,4 +1,4 @@
-import { arrayContentEquals, arrayContentStartsWith } from "./arrays";
+import { arrayContentEquals, arrayContentStartsWith } from "./arrays.ts";
 
 describe("array", () => {
   describe("arrayContentEquals", () => {
diff --git a/packages/utils/src/assert.spec.ts b/packages/utils/src/assert.spec.ts
index 4e36c45514..87cda0370b 100644
--- a/packages/utils/src/assert.spec.ts
+++ b/packages/utils/src/assert.spec.ts
@@ -1,4 +1,4 @@
-import { assert, assertDefined, assertDefinedAndNotNull } from "./assert";
+import { assert, assertDefined, assertDefinedAndNotNull } from "./assert.ts";
 
 describe("assert", () => {
   describe("assert", () => {
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index 624348188b..fe611cd975 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -1,4 +1,4 @@
-export { arrayContentEquals, arrayContentStartsWith } from "./arrays";
-export { assert, assertDefined, assertDefinedAndNotNull } from "./assert";
-export { sleep } from "./sleep";
-export { isDefined, isNonNullObject, isUint8Array } from "./typechecks";
+export { arrayContentEquals, arrayContentStartsWith } from "./arrays.ts";
+export { assert, assertDefined, assertDefinedAndNotNull } from "./assert.ts";
+export { sleep } from "./sleep.ts";
+export { isDefined, isNonNullObject, isUint8Array } from "./typechecks.ts";
diff --git a/packages/utils/src/sleep.spec.ts b/packages/utils/src/sleep.spec.ts
index 579890ca86..14dbc3f9b8 100644
--- a/packages/utils/src/sleep.spec.ts
+++ b/packages/utils/src/sleep.spec.ts
@@ -1,4 +1,4 @@
-import { sleep } from "./sleep";
+import { sleep } from "./sleep.ts";
 
 describe("sleep", () => {
   it("resolves after at least x milliseconds", async () => {
diff --git a/packages/utils/src/typechecks.spec.ts b/packages/utils/src/typechecks.spec.ts
index 074493bd82..42e7492aac 100644
--- a/packages/utils/src/typechecks.spec.ts
+++ b/packages/utils/src/typechecks.spec.ts
@@ -1,4 +1,4 @@
-import { isDefined, isNonNullObject, isUint8Array } from "./typechecks";
+import { isDefined, isNonNullObject, isUint8Array } from "./typechecks.ts";
 
 describe("typechecks", () => {
   describe("isNonNullObject", () => {
diff --git a/tsconfig.json b/tsconfig.json
index c678ea51f0..2208876555 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -22,6 +22,7 @@
     "pretty": true,
     "removeComments": false,
     "resolveJsonModule": true,
+    "rewriteRelativeImportExtensions": true,
     "sourceMap": true,
     "strict": true
   }