compress

compress compresses HTTP responses with zstd, br (Brotli) or gzip, chosen from the client's Accept-Encoding header.

server:
  http:
    middlewares:
      compress:
        compress: {}

Fields

Field	Default	Description
encodings	[zstd, br, gzip]	Enabled encodings in server preference order.
min_length	1024	Responses smaller than this (bytes) are sent uncompressed.
excluded_content_types	see below	Content types that are never compressed. type/* wildcards are supported.
included_content_types		When set, only these content types are compressed.
gzip_level	-1 (default)	gzip level, 1-9.
brotli_level	4	Brotli quality, 0-11. Use higher values only for cached static content.
zstd_level	3	zstd level, 1-22, mapped to the closest encoder speed.

Encoding selection

The encoding with the highest q value in Accept-Encoding wins. When several share the same quality, the order of encodings decides. * matches every enabled encoding and q=0 disables one.

Accept-Encoding	Result
gzip, deflate, br, zstd	zstd
gzip, br	br
gzip;q=1, br;q=0.5	gzip
identity	not compressed

Skipped responses

Responses are passed through unchanged when:

• the request is a HEAD, Range or WebSocket upgrade request,
• the status is 1xx, 204, 206 or 304,
• the response already has Content-Encoding or Content-Range,
• Cache-Control contains no-transform,
• the content type is excluded,
• the body is smaller than min_length.

The default excluded types are already compressed formats: image/* (except image/svg+xml, image/bmp and icons), video/*, audio/*, font/woff, font/woff2, archive types, application/octet-stream and application/grpc. Setting excluded_content_types replaces this list.

Notes

• Vary: Accept-Encoding is always added.
• A strong ETag is converted to a weak one when the body is compressed.
• Accept-Encoding is removed from the request before calling the next handler, so a proxied upstream sends an uncompressed body and turna compresses it once.
• Flushed (streaming / SSE) responses are compressed and flushed immediately.

Use decompress to decode compressed request bodies.