Fastify compression utils
npm install @fastify/compress
Adds compression utils to the Fastify reply object and a hook to decompress requests payloads.
Supports gzip, deflate, brotli, and zstd (Node.js 22.15+/23.8+).
> ℹ️ Note: In large-scale scenarios, use a proxy like Nginx to handle response compression.
> ⚠ Warning: Since @fastify/compress version 4.x, payloads compressed with the zip algorithm are not automatically uncompressed. This plugin focuses on response compression, and zip is not in the IANA Table of Content Encodings.
npm i @fastify/compress
$3
| Plugin version | Fastify version |
| ---------------|-----------------|
| | ^5.x |
| >=6.x <8.x | ^4.x |
| >=3.x <6.x | ^3.x |
| ^2.x | ^2.x |
| >=0.x <2.x | ^1.x |
Please note that if a Fastify version is out of support, then so are the corresponding versions of this plugin
in the table above.
See Fastify's LTS policy for more details.
Usage - Compress replies
This plugin adds two functionalities to Fastify: a compress utility and a global compression hook.
Currently, the following encoding tokens are supported, using the first acceptable token in this order:
1.
zstd (Node.js 22.15+/23.8+)
2. br
3.
4.
5. (no preference — @fastify/compress will use gzip)
6. identity (no compression)If an unsupported encoding is received or the
'accept-encoding' header is missing, the payload will not be compressed.
To return an error for unsupported encoding, use the onUnsupportedEncoding option.The plugin compresses payloads based on
content-type. If absent, it assumes application/json.$3
The global compression hook is enabled by default. To disable it, pass { global: false }:
`js
await fastify.register(
import('@fastify/compress'),
{ global: false }
)
`If only compression or decompression is required, set the
or globalDecompression config flags to false respectively (both are true by default).`js
await fastify.register(
import('@fastify/compress'),
// Disable compression but keep decompression enabled (default behavior for globalDecompression is true)
{ globalCompression: false }
)// Disable decompression but keep compression enabled
await fastify.register(
import('@fastify/compress'),
{ globalDecompression: false }
)
`Fastify encapsulation can be used to set global compression but run it only in a subset of routes by wrapping them inside a plugin.
> ℹ️ Note: If using
plugin together with @fastify/static plugin, @fastify/compress must be registered (with global hook) before registering @fastify/static.$3
Different compression options can be specified per route using the compress options in the route's configuration.
Setting compress: false on any route will disable compression on the route even if global compression is enabled.
`js
await fastify.register(
import('@fastify/compress'),
{ global: false }
)// only compress if the payload is above a certain size and use brotli
fastify.get('/custom-route', {
compress: {
inflateIfDeflated: true,
threshold: 128,
zlib: {
createBrotliCompress: () => createYourCustomBrotliCompress(),
createGzip: () => createYourCustomGzip(),
createDeflate: () => createYourCustomDeflate()
}
}, (req, reply) => {
// ...
})
`$3
This plugin adds a method to reply that compresses a stream or string based on the accept-encoding header. If a JS object is passed, it will be stringified to JSON.The
compress method uses per-route parameters if configured, otherwise it uses global parameters.`js
import fs from 'node:fs'
import fastify from 'fastify'const app = fastify()
await app.register(import('@fastify/compress'), { global: false })
app.get('/', (req, reply) => {
reply
.type('text/plain')
.compress(fs.createReadStream('./package.json'))
})
await app.listen({ port: 3000 })
`It's also possible to pass a Fetch API
object or a Web ReadableStream. The plugin will automatically extract the body stream from the Response or convert the Web stream to a Node.js Readable behind the scenes.`js
import fastify from 'fastify'const app = fastify()
await app.register(import('@fastify/compress'), { global: true })
app.get('/', async (req, reply) => {
const resp = new Response('Hello from Fetch Response')
reply.compress(resp)
})
`js
app.get('/', async (req, reply) => {
return new Response('Hello from Fetch Response')
})
`js
app.get('/', (req, reply) => {
const stream = new ReadableStream({
start (controller) {
controller.enqueue(new TextEncoder().encode('Hello from Web ReadableStream'))
controller.close()
}
}) reply.header('content-type', 'text/plain')
reply.compress(stream)
})
`Compress Options
$3
The minimum byte size for response compression. Defaults to .
`js
await fastify.register(
import('@fastify/compress'),
{ threshold: 2048 }
)
`
$3
mime-db determines if a should be compressed. Additional content types can be compressed via regex or a function.`js
await fastify.register(
import('@fastify/compress'),
{ customTypes: /x-protobuf$/ }
)
`or
js
await fastify.register(
import('@fastify/compress'),
{ customTypes: contentType => contentType.endsWith('x-protobuf') }
)
`$3
Set to send a custom error response for unsupported encoding. The function can modify the reply and return a string | Buffer | Stream | Error payload.`js
await fastify.register(
import('@fastify/compress'),
{
onUnsupportedEncoding: (encoding, request, reply) => {
reply.code(406)
return 'We do not support the ' + encoding + ' encoding.'
}
}
)
`$3
Response compression can be disabled by an header in the request.$3
Optional feature to inflate pre-compressed data if the client does not include one of the supported compression types in its accept-encoding header.
`js
await fastify.register(
import('@fastify/compress'),
{ inflateIfDeflated: true }
)fastify.get('/file', (req, reply) =>
// will inflate the file on the way out for clients
// that indicate they do not support compression
reply.send(fs.createReadStream('./file.gz')))
`$3
By default, prioritizes compression as described here. Change this by passing an array of compression tokens to the encodings option:`js
await fastify.register(
import('@fastify/compress'),
// Only support gzip and deflate, and prefer deflate to gzip
{ encodings: ['deflate', 'gzip'] }
)// Example with zstd support (Node.js 22.15+/23.8+)
await fastify.register(
import('@fastify/compress'),
// Prefer zstd, fallback to brotli, then gzip
{ encodings: ['zstd', 'br', 'gzip'] }
)
`$3
Compression can be tuned with and zlibOptions, which are passed directly to native node zlib methods. See class definitions.`js
server.register(fastifyCompress, {
brotliOptions: {
params: {
[zlib.constants.BROTLI_PARAM_MODE]: zlib.constants.BROTLI_MODE_TEXT, // useful for APIs that primarily return text
[zlib.constants.BROTLI_PARAM_QUALITY]: 4, // default is 4, max is 11, min is 0
},
},
zlibOptions: {
level: 6, // default is typically 6, max is 9, min is 0
}
});
`$3
By default, removes the reply Content-Length header. Change this by setting removeContentLengthHeader to false globally or per route.`js
// Global plugin scope
await server.register(fastifyCompress, { global: true, removeContentLengthHeader: false }); // Route-specific scope
fastify.get('/file', {
compress: { removeContentLengthHeader: false }
}, (req, reply) =>
reply.compress(fs.createReadStream('./file.gz'))
)
`Usage - Decompress request payloads
This plugin adds a hook to decompress the request payload based on the content-encoding request header.Currently, the following encoding tokens are supported:
-
zstd (Node.js 22.15+/23.8+)
- br
-
- If an unsupported encoding or invalid payload is received, the plugin throws an error.
If the request header is missing, the plugin yields to the next hook.
$3
The plugin supports compressing the following payload types:
- Strings and Buffers
- Node.js streams
- Response objects (from the Fetch API)
- ReadableStream objects (from the Web Streams API)
$3
The global request decompression hook is enabled by default. To disable it, pass
:
`js
await fastify.register(
import('@fastify/compress'),
{ global: false }
)
`Fastify encapsulation can be used to set global decompression but run it only in a subset of routes by wrapping them inside a plugin.
$3
Specify different decompression options per route using the
options in the route's configuration.
`js
await fastify.register(
import('@fastify/compress'),
{ global: false }
)// Always decompress using gzip
fastify.get('/custom-route', {
decompress: {
forceRequestEncoding: 'gzip',
zlib: {
createBrotliDecompress: () => createYourCustomBrotliDecompress(),
createGunzip: () => createYourCustomGunzip(),
createInflate: () => createYourCustomInflate()
}
}
}, (req, reply) => {
// ...
})
`$3
By default,
accepts all encodings specified here. Change this by passing an array of compression tokens to the requestEncodings option:`js
await fastify.register(
import('@fastify/compress'),
// Only support gzip
{ requestEncodings: ['gzip'] }
)// Example with zstd support for request decompression (Node.js 22.15+/23.8+)
await fastify.register(
import('@fastify/compress'),
// Support zstd, brotli and gzip for request decompression
{ requestEncodings: ['zstd', 'br', 'gzip'] }
)
`$3
By default,
chooses the decompression algorithm based on the content-encoding header.One algorithm can be forced, and the header ignored, by providing the
forceRequestEncoding option.If the request payload is not compressed,
@fastify/compress will try to decompress, resulting in an error.$3
The response error can be customized for unsupported request payload encoding by setting
onUnsupportedEncoding(request, encoding) to a function that returns an error.`js
await fastify.register(
import('@fastify/compress'),
{
onUnsupportedRequestEncoding: (request, encoding) => {
return {
statusCode: 415,
code: 'UNSUPPORTED',
error: 'Unsupported Media Type',
message: 'We do not support the ' + encoding + ' encoding.'
}
}
}
)
`$3
The response error can be customized for undetectable request payloads by setting
to a function that returns an error.`js
await fastify.register(
import('@fastify/compress'),
{
onInvalidRequestPayload: (request, encoding, error) => {
return {
statusCode: 400,
code: 'BAD_REQUEST',
error: 'Bad Request',
message: 'This is not a valid ' + encoding + ' encoded payload: ' + error.message
}
}
}
)
``Past sponsors:
- LetzDoIt
Licensed under MIT.