fastify-uws

A performant HTTP and WebSocket server for Fastify with uWebSockets.

Installation

Install fastify-uws with your favorite package manager:

$ npm i fastify-uws
# or
$ yarn add fastify-uws
# or
$ pnpm i fastify-uws
# or
$ bun add fastify-uws

Supported

fastify-uws v2.x supports the following versions:

• Node.js: v20, v22, and v24
• fastify: v5.x
• @fastify/websocket: v11.x

Breaking Changes from v1.x

While fastify-uws v1.x supports the same Node.js, fastify, and @fastify/websocket versions as v2.x, the eventsource API has been removed in v2.x as Fastify now provides official Server-Sent Events (SSE) support via @fastify/sse.

- import { eventsource } from 'fastify-uws';
+ import sse from '@fastify/sse';

Usage

Just two lines are needed to speed up your Fastify application.

// app.ts
import fastify from 'fastify';
import { serverFactory } from 'fastify-uws'; // Import here

import router from '~/plugins/router';

export default () => {
  const app = fastify({
    logger: {
      transport: {
        target: '@fastify/one-line-logger',
      },
    },
    serverFactory, // And use here
  });

  app.register(router);

  return app;
};

// server.ts
import app from './app';

const server = app();

const start = async () => {
  try {
    await server.listen({
      host: '127.0.0.1',
      port: 3000,
    });
  } catch (err) {
    server.log.error(err);
    process.exit(1);
  }
};

start();

Use Fetch

// src/routes/hello-http/+handler.ts
import type { FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox';
import { Type } from 'typebox';

export default (async (app) => {
  app.get(
    '',
    {
      schema: {
        response: {
          200: Type.Object({
            message: Type.String(),
          }),
        },
      },
    },
    async (req, reply) => {
      return reply.send({
        message: 'Hello, World!',
      });
    },
  );
}) as FastifyPluginAsyncTypebox;

With FormData

// app.ts
import multipart from '@fastify/multipart';

app.register(multipart);

// src/routes/hello-fd/+handler.ts
import type { FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox';
import fs from 'node:fs';
import { pipeline } from 'node:stream/promises';

export default (async (app) => {
  app.post('', async (req, reply) => {
    const data = await req.file();

    data.file; // stream
    data.fields; // other parsed parts
    data.fieldname;
    data.filename;
    data.encoding;
    data.mimetype;

    await pipeline(data.file, fs.createWriteStream(data.filename));
    // or
    // await data.toBuffer(); // Buffer

    return reply.send({ message: 'ok' });
  });
}) as FastifyPluginAsyncTypebox;

Use WebSocket

Just a single line of change can speed up your WebSocket application in Fastify.

- import websocket from '@fastify/websocket';
+ import { websocket } from 'fastify-uws';

// app.ts
import { websocket } from 'fastify-uws';

app.register(websocket);

// src/routes/hello-ws/+handler.ts
import type { FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox';

export default (async (app) => {
  // $ node client-ws.mjs
  app.get('', { websocket: true }, (socket) => {
    app.log.info('Client connected');

    socket.on('message', (message: MessageEvent) => {
      console.log(`Client message: ${message}`);
      socket.send('Hello from Fastify!');
    });

    socket.on('close', () => {
      app.log.info('Client disconnected');
    });
  });
}) as FastifyPluginAsyncTypebox;

Use EventSource

// app.ts
import sse from '@fastify/sse';

app.register(sse);

// src/routes/hello-sse/+handler.ts
import type { FastifyPluginAsyncTypebox } from '@fastify/type-provider-typebox';

export default (async (app) => {
  // $ node client-es.mjs
  app.get('', { sse: true }, async (request, reply) => {
    app.log.info('Client connected');

    await reply.sse.send({ data: 'Hello from Fastify!' });

    request.raw.on('close', () => {
      app.log.info('Client disconnected');
    });
  });
}) as FastifyPluginAsyncTypebox;

TLS/SSL: http2 and https

import fs from 'node:fs';
import fastify from 'fastify';
import { serverFactory, websocket } from 'fastify-uws';
// [...]
export default () => {
  const app = fastify({
    http2: true,
    https: {
      key: fs.readFileSync(process.env.HTTPS_KEY),
      cert: fs.readFileSync(process.env.HTTPS_CERT),
    },
    logger: {
      transport: {
        target: '@fastify/one-line-logger',
      },
    },
    serverFactory,
  });

  app.register(websocket);
  // [...]
};
// [...]

Benchmarks

oha v1.4.5

$ oha -c 500 -z 10s --no-tui http://0.0.0.0:3000/api/hello-world

	Version	Language	Router	Requests/sec
hyper	1.4.1	Rust	✗	56,175.6102
warp	0.3.7	Rust	✓	55,868.5861
axum	0.7.7	Rust	✓	54,588.2828
bun	1.1.30	TypeScript/Bun	✗	54,098.4841
graphul	1.0.1	Rust	✓	53,949.4400
poem	3.1.0	Rust	✓	53,849.0781
uws	20.48.0	JavaScript/Node	✗	52,802.8029
elysia	1.1.17	TypeScript/Bun	✓	52,257.3305
				~ 5.5k ~
hyper-express	6.17.2	JavaScript/Node	✓	46,745.4887
hono	4.6.3	TypeScript/Bun	✓	46,685.6014
nhttp	2.0.2	TypeScript/Deno	✓	44,874.2535
deno	2.0.0	TypeScript/Deno	✗	44,753.8552
hono	4.6.3	TypeScript/Deno	✓	43,280.7544
				~ 9.2k ~
h3	1.12.0	TypeScript/Bun	✓	34,043.4693
fastify-uws	1.0.0	JavaScript/Node	✓	31,295.8715
polka	1.0.0-next.28	JavaScript/Node	✓	31,086.5543
oak	17.0.0	TypeScript/Deno	✓	30,730.7971
node	20.18.0	JavaScript/Node	✗	29,230.1719
oak	17.0.0	TypeScript/Bun	✓	27,449.3417
fastify	5.0.0	JavaScript/Node	✓	27,408.6679
hono	4.6.3	JavaScript/Node	✓	25,138.5659
				~ 4.9k ~
h3	1.12.0	JavaScript/Node	✓	20,193.2311
				~ 9.2k ~
express	4.21.0	JavaScript/Node	✓	10,949.1532

Credits

This project is based on @geut/fastify-uws and is licensed under the MIT License.