How to set up a WebSocket server with the ws npm package

The ws Package — Minimal WebSocket Server

The ws package is the standard bare-metal WebSocket server for Node.js. Install it:

npm install ws

Stand-alone server on a dedicated port:

const { WebSocketServer } = require('ws'); const wss = new WebSocketServer({ port: 8080 }); wss.on('connection', (ws, req) => { console.log('Client connected from', req.socket.remoteAddress); ws.on('message', (data) => { const msg = JSON.parse(data.toString()); console.log('Received:', msg); ws.send(JSON.stringify({ type: 'ack', id: msg.id })); }); ws.on('close', (code, reason) => { console.log('Client disconnected', code, reason.toString()); }); ws.on('error', (err) => { console.error('Client error:', err.message); }); ws.send(JSON.stringify({ type: 'welcome' })); }); console.log('WS server listening on ws://localhost:8080');

Attaching to an Existing HTTP Server

Pass your Express or http server instead of a port to share port 80/443:

const http = require('http'); const server = http.createServer(app); // your Express app const wss = new WebSocketServer({ server }); server.listen(3000);

WebSocket upgrade requests arrive at the same port as your HTTP routes. The ws package intercepts upgrade events automatically.