Skip to content

zstd: NGINX module for the Zstandard compression

Debian/Ubuntu installation

These docs apply to the APT package nginx-module-zstd provided by the GetPageSpeed Extras repository.

  1. Configure the APT repository as described in APT repository setup.
  2. Install the module:
sudo apt-get update
sudo apt-get install nginx-module-zstd
Show suites and architectures 
| Distro   | Suite             | Component   | Architectures   |
|----------|-------------------|-------------|-----------------|
| debian   | bookworm          | main        | amd64, arm64    |
| debian   | bookworm-mainline | main        | amd64, arm64    |
| debian   | trixie            | main        | amd64, arm64    |
| debian   | trixie-mainline   | main        | amd64, arm64    |
| ubuntu   | focal             | main        | amd64, arm64    |
| ubuntu   | focal-mainline    | main        | amd64, arm64    |
| ubuntu   | jammy             | main        | amd64, arm64    |
| ubuntu   | jammy-mainline    | main        | amd64, arm64    |
| ubuntu   | noble             | main        | amd64, arm64    |
| ubuntu   | noble-mainline    | main        | amd64, arm64    |

zstd-nginx-module - Nginx module for the Zstandard compression.

Status

Actively maintained by GetPageSpeed. This repository continues the original tokers/zstd-nginx-module by Alex Zhang, which has not seen a release since 2023. It carries HTTP correctness fixes, memory-management fixes and an RFC 9110 compliant Accept-Encoding parser on top of that base, plus a test suite and static-analysis CI.

Issues and PRs are welcome if you encounter any problems.

Prebuilt packages for RHEL/CentOS/Rocky/Alma, Fedora, Amazon Linux, SLES, Debian and Ubuntu are available as nginx-module-zstd from GetPageSpeed extras.

Synopsis

## specify the dictionary
zstd_dict_file /path/to/dict;

server {
    listen 127.0.0.1:8080;
    server_name localhost;

    location / {
        # enable zstd compression
        zstd on;
        zstd_min_length 256; # no less than 256 bytes
        zstd_comp_level 3; # set the level to 3

        proxy_pass http://foo.com;
    }
}

server {
    listen 127.0.0.1:8081;
    server_name localhost;

    location / {
        zstd_static on;
        root html;
    }
}

Directives

ngx_http_zstd_filter_module

The ngx_http_zstd_filter_module module is a filter that compresses responses using the "zstd" method. This often helps to reduce the size of transmitted data by half or even more.

zstd_dict_file

Syntax: zstd_dict_file /path/to/dict;
Default: -
Context: http

Specifies the external dictionary.

WARNING: Be careful! The content-coding registration only specifies a means to signal the use of the zstd format, and does not additionally specify any mechanism for advertising/negotiating/synchronizing the use of a specific dictionary between client and server. Use the zstd_dict_file only if you can insure that both ends (server and client) are capable of using the same dictionary (e.g. advertise with a HTTP header). See https://github.com/tokers/zstd-nginx-module/issues/2 for the details.

zstd

Syntax: zstd on | off;
Default: zstd off;
Context: http, server, location, if in location

Enables or disables zstd compression for response.

zstd_comp_level

Syntax: zstd_comp_level level;
Default: zstd_comp_level 1;
Context: http, server, location

Sets a zstd compression level of a response. Acceptable values are in the range from 1 to ZSTD_maxCLevel().

zstd_min_length

Syntax: zstd_min_length length;
Default: zstd_min_length 20;
Context: http, server, location

Sets the minimum length of a response that will be compressed by zstd. The length is determined only from the Content-Length response header field.

zstd_types

Syntax: zstd_types mime-type ...;
Default: zstd_types text/html application/wasm text/wgsl;
Context: http, server, location

Enables zstd of responses for the specified MIME types in addition to text/html. The special value * matches any MIME type.

application/wasm and text/wgsl are compressed by default: both are text-like formats served under a non-text media type, so they compress well but are easy to overlook. Specifying zstd_types explicitly replaces the defaults other than text/html, which is always included.

zstd_buffers

Syntax: zstd_buffers number size;
Default: zstd_buffers 32 4k | 16 8k;
Context: http, server, location

Sets the number and size of buffers used to compress a response. By default the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform.

ngx_http_zstd_static_module

The ngx_http_zstd_static_module module allows sending precompressed files with the .zst filename extension instead of regular files.

zstd_static

Syntax: zstd_static on | off | always;
Default: zstd_static off;
Context: http, server, location

Enables ("on") or disables ("off") checking the existence of precompressed files. The following directives are also taken into account: gzip_vary.

With the "always" value, "zstd" file is used in all cases, without checking if the client supports it.

When no .zst file exists the request is declined unchanged, so gzip_static and the gzip filter still apply as they normally would.

Variables

ngx_http_zstd_filter_module

$zstd_ratio

Achieved compression ratio, computed as the ratio between the original and compressed response sizes.