Grant proposal for x402 polkadot

[crypto-priest]

Project Abstract

x402 is an open HTTP payment protocol that enables instant, programmatic micropayments directly over HTTP using the 402 Payment Required status code. We are implementing the first native x402 facilitator and SDK suite for the Polkadot ecosystem, allowing AI agents and applications to make autonomous payments using DOT and USDT on Polkadot AssetHub. Currently, x402 only exists on Base and Solana, leaving Polkadot absent from the emerging AI agent economy (projected to influence $30 trillion in transactions by 2030). Our implementation includes TypeScript/JavaScript and Rust SDKs, a production-ready facilitator service, comprehensive developer tools, and starter templates. This positions Polkadot to compete in the rapidly growing machine-to-machine payment market while providing developers with production-ready infrastructure for building paid APIs, autonomous agent applications, and pay-per-use content platforms.

Grant level

• Level 1: Up to $10,000, 2 approvals
• Level 2: Up to $30,000, 3 approvals
• Level 3: Unlimited, 5 approvals (for >$100k: Web3 Foundation Council approval)

Application Checklist

• The application template has been copied and aptly renamed (x402_polkadot.md).
• I have read the application guidelines.
• Payment details have been provided (Polkadot AssetHub (USDC & DOT) address: 12ECJeQWJBt2UVfyMQfsLca7M9aXRVzcJmbh2RvRv9yaAiwW).
• I understand that an agreed upon percentage (50%) of each milestone will be paid in vested DOT, to the Polkadot address listed in the application.
• I am aware that, in order to receive a grant, I (and the entity I represent) have to successfully complete a KYC/KYB check.
• The software delivered for this grant will be released under an open-source license (Apache 2.0) specified in the application.
• The initial PR contains only one commit (squash and force-push if needed).
• The grant will only be announced once the first milestone has been accepted (see the announcement guidelines).
• I prefer the discussion of this application to take place in a private Element/Matrix channel. My username is: @_______:matrix.org (change the homeserver if you use a different one)

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[crypto-priest]

I have read and hereby sign the Contributor License Agreement.

[keeganquigley]

Hi @crypto-priest thanks for the application. We're very interested in x402 but I think for this price tag, we would need to see some kind of working prototype. Additionally we'd need to have a pitch call with you.

Would you be willing to lower the scope to an MVP first? Can you please also fix the level in the application to mark level 3?

[crypto-priest]

Hey @keeganquigley Thank you so much for your interest. We can totally spin up an MVP to demonstrate an end to end x402 system. Here’s what we can include in the MVP:

1. A Typescript client that would make the request to paid endpoints
2. A Rust server that would host the paid endpoints and accept the request from the Typescript client
3. A mock facilitator that submits signed transactions to the blockchain and reports to the server

We can use bits and pieces from this MVP in our actual milestones for the duration of the grant.
Also, we thought we wouldn’t need the W3F council approval for asks of up to 100,000k USD, as mentioned in the application template. Can you please clarify this?
Thanks!

[keeganquigley]

Thanks @crypto-priest that's correct, anything from $30k to $100k is not subject to council approval, but must meet our new guidelines. Anything $100k or over would be subject to council approval.

[crypto-priest]

Hey @keeganquigley! Thank you for the clarification. With that out of the way please allow us time till the end of this month to develop a full-fledged MVP as mentioned above and then we can discuss further about our application?

[keeganquigley]

Thanks @crypto-priest sounds good. In the meantime, can you also take a look at this other x402 application that was submitted to the Open Source Bounty and provide a comparison? Thanks!

[crypto-priest]

Hey @keeganquigley!

We have started working on the MVP and things are looking good so far.
The other application aims to build the same product as ours, and the only difference we could find was in the deliverables. We are additionally delivering the following:

1. Rust SDK for x402

• Full x402-polkadot-rs crate with client + server modules

2. Production-Ready Templates (Total: 5)

• TypeScript: Next.js, Express
• Rust: Actix, Axum, Rocket

3. Testing CLI in Rust

Full-featured x402-cli for:

• Mock facilitator
• Payment testing
• Signature verification
• Local development

4. End-to-End Documentation and Product Website

• Complete documentation website (Docusaurus)
• Project landing/marketing website
• Integration Tutorials

Also, we have successfully released an Open Source Rust template for x402 in Solana, furthering our research and development in the field.

[crypto-priest]

Hey @keeganquigley! Thanks for waiting. We are done with the MVP and you can find the repository here: https://github.com/X402-Polkadot/x402-polkadot The README walks you thru running this whole project.

Additionally, we have deployed the frontend service and other backend services (faciliator and server) for ease of testing. You can find the deployed client at: https://x402-client.fly.dev

Please let us know if you face any difficulty testing it.
This covers a very high-level overview of how x402 on Polkadot would look like. Feedbacks appreciated.

[keeganquigley]

Hey @crypto-priest thanks for sending the links. Much obliged. Two of the tests work but for some reason the paid endpoint is failing. Any idea what the issue might be?

[crypto-priest]

Hey @keeganquigley!
Sorry for the inconvenience. The polkadot testnet node we were using for the RPC call was down, hence the API failed. But we have added a fallback mechanism that detects if a node is down and requests an alternate node. Can you check now if it works for you? Here's a screenshot of when it worked for us. Please let us know if you face any issues.

[keeganquigley]

Thanks @crypto-priest it's working now! Looks nice. I will mark the application as ready for review, however the grants program generally focuses on early-stage proof-of-concepts, meaning we don't pay to get the code production ready.

Year 1: The grant funding ($100,000 USD) will cover development, infrastructure, and gas fees for the first year of operation

Therefore we typically don't cover infra costs, cloud hosting, gas fees, etc. As I previously mentioned, my recommendation would still be to reduce the scope to a smaller amount and duration, for example a level 2 grant over three months. That gives us a chance to see some of your work and then you can always apply for a subsequent grant down the line. But we'll see if others disagree.