MCP HTTP Proxy

Expose any stdio-based MCP server (like @browsermcp/mcp) to the internet via HTTP/SSE transport. Perfect for remote agents that need to access MCP tools over a network.

Features

• 🌐 Standard MCP SSE Transport - Follows MCP HTTP transport specification
• 🔐 API Key Authentication - Secure access with Bearer token
• 🚀 Multiple Exposure Options - Tailscale, ngrok, Cloudflare Tunnel
• 🔄 Session Management - Multiple concurrent sessions supported
• 📦 Works with any MCP server - Defaults to @browsermcp/mcp

Quick Start

1. Install Dependencies

npm install

2. Configure (Optional)

cp .env.example .env
# Edit .env to set your API key

Generate a secure API key:

node -e "console.log(require('crypto').randomBytes(32).toString('hex'))"

3. Build and Run

npm run build
npm start

Or for development:

npm run dev

API Endpoints (Standard MCP SSE Transport)

Endpoint	Method	Description
/sse	GET	Establish SSE connection (returns endpoint URL)
/message?sessionId=xxx	POST	Send JSON-RPC messages
/health	GET	Health check (no auth required)
/sessions	GET	List active sessions (auth required)

Exposing to the Internet

Option 1: Tailscale (Recommended for Private Access)

Tailscale provides secure, private access without exposing to the public internet.

# Install Tailscale if not already installed
# Then serve via Tailscale
tailscale serve --bg --http 3000

Or use your Tailscale IP directly:

tailscale status  # Find your Tailscale IP

Your MCP server will be available at:

• https://your-machine.tailnet-name.ts.net (via serve)
• http://your-tailscale-ip:3000 (direct IP)

Use from your agent:

{
  "mcpServers": {
    "browser-remote": {
      "url": "http://your-tailscale-ip:3000/sse",
      "headers": {
        "Authorization": "Bearer your-api-key"
      }
    }
  }
}

Option 2: ngrok (Public URL)

# Install ngrok if not already installed
ngrok http 3000

ngrok will provide a public URL like https://abc123.ngrok.io.

Option 3: Cloudflare Tunnel

# Install cloudflared if not already installed
cloudflared tunnel --url http://localhost:3000

How the SSE Transport Works

1. Client GETs /sse - Server creates session, sends endpoint event with message URL
2. Client POSTs to /message?sessionId=xxx - Server forwards JSON-RPC to MCP process
3. Server streams responses - MCP responses sent as SSE message events

Usage Examples

Test Health Check

curl http://localhost:3000/health

Response:

{
  "status": "healthy",
  "sessions": 0,
  "uptime": 10.5,
  "transport": "sse",
  "endpoints": {
    "sse": "/sse (GET - establishes SSE connection)",
    "message": "/message?sessionId=xxx (POST - send JSON-RPC messages)"
  }
}

Connect via SSE (JavaScript)

const eventSource = new EventSource('http://localhost:3000/sse', {
  headers: { 'Authorization': 'Bearer your-api-key' }
});

eventSource.addEventListener('endpoint', (e) => {
  console.log('Message endpoint:', e.data);
  // e.data = "/message?sessionId=xxx"
});

eventSource.addEventListener('message', (e) => {
  console.log('MCP response:', JSON.parse(e.data));
});

Send MCP Request

curl -X POST "http://localhost:3000/message?sessionId=your-session-id" \
  -H "Authorization: Bearer your-api-key" \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Configuration

Environment Variable	Description	Default
PORT	Server port	3000
HOST	Host to bind to	0.0.0.0
MCP_API_KEY	API key for authentication	(none)
MCP_COMMAND	Command to run MCP server	npx
MCP_ARGS	JSON array of arguments	["@browsermcp/mcp@latest"]

Using Different MCP Servers

You can use this proxy with any stdio-based MCP server:

# Example: Use a custom MCP server
MCP_COMMAND=node
MCP_ARGS=["/path/to/your/mcp-server/dist/index.js"]

# Example: Use Python MCP server
MCP_COMMAND=python
MCP_ARGS=["-m", "your_mcp_server"]

Security Notes

1. Always use API key authentication when exposing to the internet
2. Use HTTPS (Tailscale, ngrok, and Cloudflare all provide this)
3. Tailscale is recommended for private access within your tailnet
4. Rotate API keys periodically
5. Monitor sessions via /sessions endpoint

Troubleshooting

MCP Server Not Starting

Check the console logs for errors. The MCP server stderr is forwarded to the proxy's console.

Connection Refused

• Ensure server is running: curl http://localhost:3000/health
• Check Tailscale connectivity: tailscale status

Authentication Failed

• Check the API key in .env matches your request header
• Ensure "Bearer " prefix is included in Authorization header

SSE Not Working

• Ensure you're connecting to /sse endpoint (not just base URL)
• Check that Authorization header is sent with GET request too

License

MIT