An efficient server implies a lower cost of the infrastructure, a 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 as 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 v4 release. Check out the v3.x branch for v3.

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:

Install with npm:

npm i fastify

Install with yarn:

yarn add 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.

Fastify v1.x and v2.x

Code for Fastify's v1.x is in branch 1.x, so all Fastify 1.x related changes should be based on branch 1.x. In a similar way, all Fastify v2.x related changes should be based on branch 2.x.

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 deciding to listen 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 to use 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 the developer 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

Benchmarks taken using 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.

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

Great Contributors

Great contributors on a specific area in the Fastify ecosystem will be invited to join this group by Lead Maintainers.

Past Collaborators

Hosted by

We are a Growth Project in the OpenJS Foundation.

Acknowledgements

This project is kindly sponsored by:

Past Sponsors:

LetzDoIt

This list includes all companies that support one or more of the team members in the maintainance of 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

Project Name	Stars	Repos Using This	Packages Using This	Most Recent Commit	Total Releases	Latest Release	Open Issues	License	Language
Fastify	28,588	1,131	2,639	a day ago	264	July 27, 2023	78	other	JavaScript
Fast and low overhead web framework, for Node.js
Echo	26,636		2,514	7 days ago	171	July 16, 2023	77	mit	Go
High performance, minimalist Go web framework
Buffalo	7,776	149	91	2 months ago	174	January 26, 2023	26	mit	Go
Rapid Web Development w/ Go
Go Web Framework Benchmark	1,911			a month ago	1	February 14, 2021	18	apache-2.0	Go
:zap: Go web framework benchmark
Sauron	1,816	2	9	10 days ago	107	August 28, 2023		mit	Rust
A versatile web framework and library for building client-side and server-side web applications
Py Frameworks Bench	663			a year ago			14	mit	Python
Another benchmark for some python frameworks
Cottage	100	4	4	4 years ago	13	October 29, 2019	4		JavaScript
Simple, fast HTTP router on koa.js.
Webpp	89			2 days ago			239	mit	C++
C++ web framework \| web development can be done with C++ as well.
Procyon	57		3	6 months ago	11	June 17, 2021	1	apache-2.0	Go
Procyon is a powerful http web framework written in Go. "Build your application fast".
Zap	53			5 years ago	4	November 13, 2017	1	mit	Rust
:zap: fast http framework for rust

Fastify

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