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Fastify

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.

This branch refers to the upcoming 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-appcd 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

If installing in an existing project, then Fastify can be installed into the project as a dependency:

Install with npm:

npm i fastify@next

Install with yarn:

yarn add fastify@next

Example

// Require the framework and instantiate it// ESMimport Fastify from 'fastify'const fastify = Fastify({  logger: true})// CommonJsconst fastify = require('fastify')({  logger: true})// Declare a routefastify.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:

// ESMimport Fastify from 'fastify'const fastify = Fastify({  logger: true})// CommonJsconst 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.
  • Extendible: 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.

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
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