An efficient server implies a lower cost of the infrastructure, better responsiveness under load, and happy users. How can you efficiently handle the resources of your server, knowing that you are serving the highest number of requests possible, without sacrificing security validations and handy development?

Enter Fastify. Fastify is a web framework highly focused on providing the best developer experience with the least overhead and a powerful plugin architecture. It is inspired by Hapi and Express and as far as we know, it is one of the fastest web frameworks in town.

The main branch refers to the Fastify v5 release. Check out the 4.x branch for v4.

Quick start

Create a folder and make it your current working directory:

mkdir my-app
cd my-app

Generate a fastify project with npm init:

npm init fastify

Install dependencies:

npm i

To start the app in dev mode:

npm run dev

For production mode:

npm start

Under the hood npm init downloads and runs Fastify Create, which in turn uses the generate functionality of Fastify CLI.

Install

To install Fastify in an existing project as a dependency:

npm i fastify

Example

// Require the framework and instantiate it

// ESM
import Fastify from 'fastify'

const fastify = Fastify({
  logger: true
})
// CommonJs
const fastify = require('fastify')({
  logger: true
})

// Declare a route
fastify.get('/', (request, reply) => {
  reply.send({ hello: 'world' })
})

// Run the server!
fastify.listen({ port: 3000 }, (err, address) => {
  if (err) throw err
  // Server is now listening on ${address}
})

With async-await:

// ESM
import Fastify from 'fastify'

const fastify = Fastify({
  logger: true
})
// CommonJs
const fastify = require('fastify')({
  logger: true
})

fastify.get('/', async (request, reply) => {
  reply.type('application/json').code(200)
  return { hello: 'world' }
})

fastify.listen({ port: 3000 }, (err, address) => {
  if (err) throw err
  // Server is now listening on ${address}
})

Do you want to know more? Head to the Getting Started. If you learn best by reading code, explore the official demo.

Note

.listen binds to the local host, localhost, interface by default (127.0.0.1 or ::1, depending on the operating system configuration). If you are running Fastify in a container (Docker, GCP, etc.), you may need to bind to 0.0.0.0. Be careful when listening on all interfaces; it comes with inherent security risks. See the documentation for more information.

Core features

Highly performant: as far as we know, Fastify is one of the fastest web frameworks in town, depending on the code complexity we can serve up to 76+ thousand requests per second.
Extensible: Fastify is fully extensible via its hooks, plugins, and decorators.
Schema-based: even if it is not mandatory we recommend using JSON Schema to validate your routes and serialize your outputs. Internally Fastify compiles the schema in a highly performant function.
Logging: logs are extremely important but are costly; we chose the best logger to almost remove this cost, Pino!
Developer friendly: the framework is built to be very expressive and help developers in their daily use without sacrificing performance and security.

Benchmarks

Machine: EX41S-SSD, Intel Core i7, 4Ghz, 64GB RAM, 4C/8T, SSD.

Method:: autocannon -c 100 -d 40 -p 10 localhost:3000 * 2, taking the second average

Framework	Version	Router?	Requests/sec
Express	4.17.3	✓	14,200
hapi	20.2.1	✓	42,284
Restify	8.6.1	✓	50,363
Koa	2.13.0	✗	54,272
Fastify	4.0.0	✓	77,193
-
`http.Server`	16.14.2	✗	74,513

These benchmarks taken using https://github.com/fastify/benchmarks. This is a synthetic "hello world" benchmark that aims to evaluate the framework overhead. The overhead that each framework has on your application depends on your application. You should always benchmark if performance matters to you.

Documentation

Ecosystem

Core - Core plugins maintained by the Fastify team.
Community - Community-supported plugins.
Live Examples - Multirepo with a broad set of real working examples.
Discord - Join our discord server and chat with the maintainers.

Support

Please visit Fastify help to view prior support issues and to ask new support questions.

Version 3 of Fastify and lower are EOL and will not receive any security or bug fixes.

Fastify's partner, HeroDevs, provides commercial security fixes for all unsupported versions at https://herodevs.com/support/fastify-nes. Fastify's supported version matrix is available in the Long Term Support documentation.

Contributing

Whether reporting bugs, discussing improvements and new ideas, or writing code, we welcome contributions from anyone and everyone. Please read the CONTRIBUTING guidelines before submitting pull requests.

Team

Fastify is the result of the work of a great community. Team members are listed in alphabetical order.

Lead Maintainers:

Fastify Core team

Fastify Plugins team

Emeritus Contributors

Great contributors to a specific area of the Fastify ecosystem will be invited to join this group by Lead Maintainers when they decide to step down from the active contributor's group.

Hosted by

We are an At-Large Project in the OpenJS Foundation.

Sponsors

Support this project by becoming a SPONSOR! Fastify has an Open Collective page where we accept and manage financial contributions.

Acknowledgments

This project is kindly sponsored by:

Past Sponsors:

LetzDoIt

This list includes all companies that support one or more team members in maintaining this project.

License

Licensed under MIT.

For your convenience, here is a list of all the licenses of our production dependencies:

MIT
ISC
BSD-3-Clause
BSD-2-Clause

License

metcoder95/fastify

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