fastify/docs/Reference/HTTP2.md

Fast and low overhead web framework, for Node.js

<h1 align="center">Fastify</h1>

## HTTP2

_Fastify_ supports HTTP2 over either HTTPS (h2) or plaintext (h2c).

Currently, none of the HTTP2-specific APIs are available through _Fastify_, but
Node's `req` and `res` can be accessed through our `Request` and `Reply`
interface. PRs are welcome.

### Secure (HTTPS)

HTTP2 is supported in all modern browsers __only over a secure connection__:

```js
'use strict'

const fs = require('node:fs')
const path = require('node:path')
const fastify = require('fastify')({
  http2: true,
  https: {
    key: fs.readFileSync(path.join(__dirname, '..', 'https', 'fastify.key')),
    cert: fs.readFileSync(path.join(__dirname, '..', 'https', 'fastify.cert'))
  }
})

fastify.get('/', function (request, reply) {
  reply.code(200).send({ hello: 'world' })
})

fastify.listen({ port: 3000 })
```

[ALPN negotiation](https://datatracker.ietf.org/doc/html/rfc7301) allows
support for both HTTPS and HTTP/2 over the same socket.
Node core `req` and `res` objects can be either
[HTTP/1](https://nodejs.org/api/http.html) or
[HTTP/2](https://nodejs.org/api/http2.html). _Fastify_ supports this out of the
box:

```js
'use strict'

const fs = require('node:fs')
const path = require('node:path')
const fastify = require('fastify')({
  http2: true,
  https: {
    allowHTTP1: true, // fallback support for HTTP1
    key: fs.readFileSync(path.join(__dirname, '..', 'https', 'fastify.key')),
    cert: fs.readFileSync(path.join(__dirname, '..', 'https', 'fastify.cert'))
  }
})

// this route can be accessed through both protocols
fastify.get('/', function (request, reply) {
  reply.code(200).send({ hello: 'world' })
})

fastify.listen({ port: 3000 })
```

You can test your new server with:

```
$ npx h2url https://localhost:3000
```

### Plain or insecure

If you are building microservices, you can connect to HTTP2 in plain text,
however, this is not supported by browsers.

```js
'use strict'

const fastify = require('fastify')({
  http2: true
})

fastify.get('/', function (request, reply) {
  reply.code(200).send({ hello: 'world' })
})

fastify.listen({ port: 3000 })
```

You can test your new server with:

```
$ npx h2url http://localhost:3000
```