The CurrConv Chrome Extension

v1.0.1

CurrConv is a local open-source Chrome extension for currency conversion. Select a foreign currency on any webpage and the extension will convert it to your preferred currency.

The currencies are converted with the Open Exchange Rates API, therefore the extension requires an API key (free).

Table of Contents

• Table of Contents
• Installation & Setup
  • Download
  • Get an API Key
  • Install the extension in Chrome.
• Updating the extension
• Removing the extension
• Configuration
  • Settings (config.json)
  • Currencies (currencies.json)
  • Applying Changes
• Reporting bugs & suggestions
• Currently working on

Installation & Setup

Download

Download with git:

git clone https://github.com/MaelkMark/currconv-chrome.git

or simply download as ZIP (Code > Download ZIP) and unzip the folder.

Get an API Key

The currencies are converted with the Open Exchange Rates API, so the extension requires an APP ID.

1. Get a free App ID from Open Exchange Rates (you can also check out their different plans).
2. Create a file named api.key in the extension folder.
3. Paste your App ID into the api.key file.

Don't write anything else in that file. Your code should look similar to this:

a02cabaf4e85d42fa5fe6de4df3c7b6e (this is just an example, not a valid App ID)

With a free plan, you can send up to 1000 requests per month, and update the conversion rates every hour. This means that if you set updateFrequencyHours in config.json to 2 or higher, you will never run out of requests.

Install the extension in Chrome.

1. Open the chrome extensions page:

   • Enter chrome://extensions/ in the address bar
   • or click the Extensions menu button (puzzle icon) and select Manage Extensions
   • or click the three dots in the top right corner and select Extensions > Manage extensions

2. Enable the Developer Mode by turning on the Developer Mode checkbox in the top right corner.

3. Click the "Load unpacked" button in the top left corner and select the folder that you downloaded (currconv).

Now the extension is installed. You may have to reload the webpages in order to use it.

Updating the extension

If you downloaded the extension with Git, you just have to pull the latest changes.

git pull

If you didn't, you have to download it as ZIP again and overwrite the files manually.

After you updated the files, open the chrome extensions page and click on the refresh button (next to the on/off toggle of the extension). Before you can use the extension you have to reload the webpages.

Removing the extension

1. Open the chrome extensions page (chrome://extensions/)
2. Click the "Remove" button on the CurrConv extension card.

Configuration

Settings (config.json)

You can customize the extension by editing the config.json file in the extension folder.

{
    "convertTo": "HUF",
    "updateFrequencyHours": 6,
    "decimals": 0,
    "maxCurrencies": null,
    "dateFormat": "hu-HU",
    "displayModule": {
        "ratesUpdated": true,
        "usage": false
    },
    "fontSize": {
        "message": 11,
        "currencies": 11,
        "ratesUpdated": 9,
        "usage": 9
    }
}

Key	Type	Description
convertTo	String	The 3-letter currency code to convert to (e.g., "USD", "EUR", "HUF").
updateFrequencyHours	Number	How often (in hours) to fetch new exchange rates. If ≥ 2, you will never run out of free API calls.
decimals	Number	Number of decimal places to display in the result.
maxCurrencies	Number/null	Limit the number of source currencies displayed if a symbol matches multiple. null means no limit.
dateFormat	String	The (BCP 47) locale format for the "Updated at" date (e.g., "en-US", "hu-HU").
displayModule	Boolean	Toggle visibility of UI elements (ratesUpdated, usage).
fontSize	Number	Font sizes (in pt) for different UI parts (message, currencies, ratesUpdated, usage).

Currencies (currencies.json)

This file maps currency symbols to their corresponding 3-letter ISO codes.

• Key: The currency symbol (e.g., $, €, kr, Ft).
• Value: A single string code (e.g., "EUR") or an array of codes (e.g., ["USD", "CAD", "AUD"]) if the symbol is used by multiple currencies.

If a selected symbol maps to multiple currencies, the extension will attempt to show conversions for all of them, up to the maxCurrencies limit in config.json.

Applying Changes

After changing the config.json, currencies.json, or api.key files, reload the web pages where you want to use the converter.

Reporting bugs & suggestions

If you would like to report a bug, suggest an improvement or contribute code, please see the contribution guide.

Currently working on

This is a list of planned features, improvements, and bug fixes. Before suggesting an improvement, please check to see whether it is already on this list.

• Recognizing the exact currency code from the following format: US $

Made with ❤️ by Márk Magyar