`@fastify/websocket`

Adds WebSocket support, letting routes handle upgraded connections.

Since Fastify 5 Spec ↗

Syntax

app.register(websocket); app.get(url, { websocket: true }, handler)

Parameters

Name	Type	Required	Description
`options`	`object`	No	Optional options forwarded to the ws server.

Returns

Promise<void> — Resolves when the plugin is registered.

Examples

import Fastify from 'fastify';
import websocket from '@fastify/websocket';

const app = Fastify();
await app.register(websocket);

app.get('/chat', { websocket: true }, (socket, req) => {
  socket.on('message', (msg) => {
    socket.send(`echo: ${msg}`);
  });
});

Notes

Mark a route with `{ websocket: true }`; the handler receives the socket and the request. Regular HTTP handlers and WebSocket handlers can share the same URL.