gb-rpc-proxy

A simple CLI tool to proxy RPC requests and bypass CORS issues during development.

🎯 Purpose

When developing web applications that interact with blockchain RPC endpoints, you often encounter CORS (Cross-Origin Resource Sharing) issues. This tool acts as a local proxy server that:

• Accepts RPC requests from your frontend application
• Forwards them to the actual RPC endpoint
• Returns the response back to your application
• Handles CORS headers automatically

📦 Installation

Global Installation (Recommended)

npm install -g gb-rpc-proxy

Local Installation

npm install gb-rpc-proxy

🚀 Usage

Basic Usage

gb-rpc https://ev-reth-eden-testnet.binarybuilders.services:8545

This will start the proxy on http://localhost:8080/rpc

Custom Port

gb-rpc https://your-rpc-endpoint.com:8545 --port 3000
# or
gb-rpc https://your-rpc-endpoint.com:8545 -p 3000

WebSocket URLs

gb-rpc wss://eth-mainnet.ws.alchemy.com/v2/YOUR-API-KEY

Help

gb-rpc --help

🔧 Usage in Your Application

Once the proxy is running, update your frontend code to use the local proxy URL:

Before (with CORS issues):

const provider = new ethers.JsonRpcProvider(
  'https://ev-reth-eden-testnet.binarybuilders.services:8545'
);

After (using the proxy):

const provider = new ethers.JsonRpcProvider(
  'http://localhost:8080/rpc'
);

📋 Endpoints

• POST /rpc - Main RPC proxy endpoint
• GET / - Health check endpoint

Health Check Response

{
  "status": "ok",
  "proxy": "gb-rpc-proxy",
  "target": "https://your-rpc-endpoint.com:8545",
  "version": "1.0.0"
}

🛠️ Development

Clone and Install

git clone <repository-url>
cd simple-rpc-proxy
npm install

Run Locally

node cli.js https://your-rpc-endpoint.com:8545

Test Locally

npm link
gb-rpc https://your-rpc-endpoint.com:8545

📝 Publishing to npm

# Login to npm (first time only)
npm login

# Publish the package
npm publish

🔒 Security Notes

• Development Only: This tool is intended for local development. Do not expose it to the internet.
• API Keys: Be careful when using RPC URLs with API keys. They will be visible in the proxy logs.
• CORS: The proxy allows all origins (*) for maximum compatibility during development.

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

MIT

👨‍💻 Author

Gabriel Barros

🙏 Acknowledgments

Built to simplify blockchain development by removing CORS headaches during local development.