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Gzip Middleware for Go

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An out-of-the-box, also customizable gzip middleware for Gin and net/http.

Golang Gzip Middleware


Use DefaultHandler() to create a ready-to-go gzip middleware.


import github.com/nanmu42/gzip

func main() {
	g := gin.Default()

    // use default settings

	g.GET("/", func(c *gin.Context) {
		c.JSON(http.StatusOK, map[string]interface{}{
			"code": 0,
			"msg":  "hello",
			"data": fmt.Sprintf("l%sng!", strings.Repeat("o", 1000)),

	log.Println(g.Run(fmt.Sprintf(":%d", 3000)))


import github.com/nanmu42/gzip

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		writeString(w, fmt.Sprintf("This content is compressed: l%sng!", strings.Repeat("o", 1000)))

    // wrap http.Handler using default settings
	log.Println(http.ListenAndServe(fmt.Sprintf(":%d", 3001), gzip.DefaultHandler().WrapHandler(mux)))

func writeString(w http.ResponseWriter, payload string) {
	w.Header().Set("Content-Type", "text/plain; charset=utf8")
	_, _ = io.WriteString(w, payload+"\n")

Customize Handler

Handler can be customized using NewHandler and Config:

import github.com/nanmu42/gzip

handler := gzip.NewHandler(gzip.Config{
    // gzip compression level to use
	CompressionLevel: 6, 
    // minimum content length to trigger gzip, the unit is in byte.
	MinContentLength: 1024,
    // RequestFilter decide whether or not to compress response judging by request.
    // Filters are applied in the sequence here.
	RequestFilter: []RequestFilter{
    // ResponseHeaderFilter decide whether or not to compress response
    // judging by response header
	ResponseHeaderFilter: []ResponseHeaderFilter{

RequestFilter and ResponseHeaderFilter are interfaces. You may define one that specially suits your need.


  • When response payload is small, the handler is smart enough to skip compression automatically, which takes neglectable overhead.
  • At the time when the payload is big enough, gzip kicks in and there is a reasonable price.
$ go test -benchmem -bench .
goos: linux
goarch: amd64
pkg: github.com/nanmu42/gzip
BenchmarkSoleGin_SmallPayload-4                          4104684               276 ns/op              64 B/op          2 allocs/op
BenchmarkGinWithDefaultHandler_SmallPayload-4            1683307               707 ns/op              96 B/op          3 allocs/op
BenchmarkSoleGin_BigPayload-4                            4198786               274 ns/op              64 B/op          2 allocs/op
BenchmarkGinWithDefaultHandler_BigPayload-4                44780             27636 ns/op             190 B/op          5 allocs/op
ok      github.com/nanmu42/gzip 6.373s

Note: due to an awkward man-mistake, benchmark of and before v1.0.0 are not accurate.


  • You should always provide a Content-Type in http response’s header, though handler guesses by http.DetectContentType()as makeshift;
  • When Content-Length is not available, handler may buffer your writes to decide if its big enough to do a meaningful compression. A high MinContentLength may bring memory overhead, although the handler tries to be smart by reusing buffers and testing if len(data) of the first http.ResponseWriter.Write(data []byte) calling suffices or not.

Status: Stable

All APIs are finalized, and no breaking changes will be made in the 1.x series of releases.


During the development of this work, the author took following works/materials as reference:

This package uses klauspost’s compress package to handle gzip compression.

Logo generated at Gopherize.me.


MIT License
Copyright (c) 2019 LI Zhennan

Caddy is licensed under the Apache License
Copyright 2015 Light Code Labs, LLC