WebSocket Echo

Upgrade HTTP requests to WebSocket connections and echo every message back from the edge using the Workers WebSocket API.

API Endpoint

GET /echo

Accepts a WebSocket upgrade and echoes each message with an echo: prefix.

Requires Upgrade: websocket on the incoming request.

Example Request

Connect with any WebSocket client:

websocat wss://your-worker.workers.dev/echo

Send hello and receive echo: hello.

Non-WebSocket Response

When the request is not a WebSocket upgrade, the worker returns HTTP 426:

{
  "error": "Expected WebSocket upgrade request (Upgrade: websocket)",
  "code": "NOT_WEBSOCKET"
}

Error Codes

• 426 - Request missing WebSocket upgrade (NOT_WEBSOCKET)

Use Cases

• Learn WebSocket upgrades with WebSocketPair in Workers
• Test real-time clients against a minimal echo server
• Prototype bidirectional edge apps before adding Durable Objects
• Debug WebSocket connectivity from browsers and CLI tools

Deployment

Local Development

cd apps/experiments/websocket-echo
npm install
npm run dev

Connect to ws://localhost:8787/echo with a WebSocket client.

Cloudflare Features Used

• Workers - Edge compute runtime
• WebSockets - WebSocketPair for bidirectional messaging