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compression-normalize: NGINX Accept-Encoding Normalization module

Installation

You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9 and 10
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
dnf -y install https://extras.getpagespeed.com/release-latest.rpm 
dnf -y install nginx-module-compression-normalize

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm 
yum -y install nginx-module-compression-normalize

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/ngx_http_compression_normalize_module.so;

This document describes nginx-module-compression-normalize v1.0.0 released on Jan 06 2026.

Describe

ngx_http_compression_normalize_module is an Nginx module designed to parse, normalize, and manage the Accept-Encoding headers from client requests. It ensures consistent handling of compression algorithms by standardizing the Accept-Encoding values, facilitating better compression management and improved vary cache performance.

Synopsis

http {
    compression_normalize_accept_encoding gzip,br,zstd gzip,br zstd br gzip;

    server {
        listen 80;
        server_name example.com;

        location / {
            # Your configurations
        }
    }
}

Directives

compression_normalize_accept_encoding

Syntax: compression_normalize_accept_encoding combinations1 [combinations2 ..] | off;

Default: compression_normalize_accept_encoding off;

Context: http, server, location

Enables the normalization of the Accept-Encoding header by specifying preferred combinations of compression algorithms. This directive accepts a list of compression methods, allowing to define the order and priority of encoding types that the server should prefer when responding to client requests.

For example, with the following configuration

compression_normalize_accept_encoding gzip,br,zstd gzip,br zstd br gzip;

If the request header Accept-Encoding contains gzip, br and zstd at the same time, the value of the standardized Accept-Encoding header is gzip,br,zstd. If the above conditions are not met, but the request header contains gzip and br, the value of the standardized Accept-Encoding header is gzip,br. And so on, until all the combinations given by the compression_normalize_accept_encoding directive are checked. If no combination is hit at this time, the Accept-Encoding header is directly deleted.

A value of off will disable this feature.

Variables

\$compression_original_accept_encoding

keeps the original value of request Accept-Encoding header.

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-compression-normalize.