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.

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}
});

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

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.

中文文档地址

Ecosystem

• 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.