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Koa Compress

Node.js CI codecov

Compress middleware for Koa


const compress = require('koa-compress')
const Koa = require('koa')

const app = new Koa()
  filter (content_type) {
  	return /text/i.test(content_type)
  threshold: 2048,
  gzip: {
    flush: require('zlib').constants.Z_SYNC_FLUSH
  deflate: {
    flush: require('zlib').constants.Z_SYNC_FLUSH,
  br: false // disable brotli




function (mimeType: string): Boolean {


An optional function that checks the response content type to decide whether to compress. By default, it uses compressible.


Minimum response size in bytes to compress. Default 1024 bytes or 1kb.


The current encodings are, in order of preference: br, gzip, deflate. Setting options[encoding] = {} will pass those options to the encoding function. Setting options[encoding] = false will disable that encoding.

Brotli compression is supported in node v11.7.0+, which includes it natively. As of v5.1.0, the default quality level is 4 for performance reasons.


An optional string, which specifies what encoders to use for requests without Accept-Encoding. Default identity.

The standard dictates to treat such requests as * meaning that all compressions are permissible, yet it causes very practical problems when debugging servers with manual tools like curl, wget, and so on. If you want to enable the standard behavior, just set defaultEncoding to *.

Manually turning compression on and off

You can always enable compression by setting ctx.compress = true. You can always disable compression by setting ctx.compress = false. This bypasses the filter check.

app.use((ctx, next) => {
  ctx.compress = true
  ctx.body = fs.createReadStream(file)