cors-dev-proxy

A minimal CLI helper to run a local development server with CORS enabled. Perfect for frontend development when you need to proxy requests to a backend server that doesn't have CORS configured.

Installation

npm install -g cors-dev-proxy
# or
pnpm add -g cors-dev-proxy
# or
yarn global add cors-dev-proxy

Usage

cors-dev-proxy [options] <command> [args...]

Options

• -i, --in <port> - Specify the port of the backend server to proxy to
• -o, --out <port> - Specify the port for the CORS proxy (default: 3000)

Examples

Start a server and automatically detect its port:

cors-dev-proxy npm run dev

Specify ports explicitly:

cors-dev-proxy -i 5173 -o 3000 npm run dev

Run with Vite:

cors-dev-proxy vite

Run with any command:

cors-dev-proxy -o 8080 node server.js

How it works

1. Spawns your command - Runs the specified command (e.g., your dev server)
2. Detects the port - Automatically detects which port your server is listening on
3. Creates a CORS proxy - Starts a proxy server that forwards requests with proper CORS headers
4. Forwards requests - All requests to the proxy are forwarded to your backend with CORS enabled

Features

• ✨ Automatic port detection - No need to specify ports if your server outputs them
• 🔄 WebSocket support - Proxies WebSocket connections too
• 🎯 Credentials support - Handles cookies and authorization headers
• 🚀 Zero configuration - Just wrap your existing dev command
• 📦 Minimal dependencies - Lightweight and fast

CORS Headers

The proxy automatically adds:

• Access-Control-Allow-Origin - Set to the request origin or *
• Access-Control-Allow-Methods - Supports GET, POST, PUT, DELETE, OPTIONS
• Access-Control-Allow-Headers - Allows all requested headers
• Access-Control-Allow-Credentials - Enabled when cookies/auth are present

License

MIT © Viktor Lázár