cors forwarding proxy on vercel

A simple Node.js script, you can deploy on Vercel to act as a CORS proxy server, adding the Access-Control-Allow-Origin header for GET requests: Feel free to clone and add your use-cases.

Deployment on Vercel:

1. Create a new Vercel project and link your code repository.
2. Make sure the script above is saved as index.js in your project root.
3. Create a vercel.json file in the root directory with the following content:

{
  "version": 2,
  "builds": [
    { "src": "index.js", "use": "@vercel/node" }
  ]
}

This configuration tells Vercel to use the @vercel/node builder for your index.js file.

5. Deploy your project to Vercel.

Usage:

Once deployed, you can use the Vercel URL of your project as a proxy for your actual API endpoint. For example, if your API endpoint is https://api.example.com/data and your Vercel URL is https://your-vercel-project.vercel.app, you can access the data with CORS headers by sending a GET request to:

https://your-vercel-project.vercel.app?url=decodedURI(https://api.example.com/data?param1=param1&p2=p2)

This will fetch data from the actual API endpoint (https://api.example.com/data), add the necessary CORS headers, and return the response to your application.

IMPORTANT="Make sure to decode the URL parameter componenet" ie. decode the thirs-party API component so that the whole URL is treated as one. Otherwise & will cause more parameters that arent handled in the script.

Remember:

• Update the allowedOrigin variable with the specific origin(s) you want to allow if you don't want to allow all origins ('*').
• Make sure to decode the API endpoint so that all extra parameters are treated as part of URL param.
• This approach provides basic CORS functionality. Consider security implications if exposing your proxy server publicly.