Compression¶

SWS provides Gzip, Deflate, Brotli and Zstandard (zstd) compression of HTTP responses.

This feature is enabled by default and can be controlled by the boolean -x, --compression option or the equivalent SERVER_COMPRESSION env.

static-web-server \
    --port 8787 \
    --root ./my-public-dir \
    --compression true

Choice of compression algorithm¶

The compression algorithm is determined by the Accept-Encoding header and the compression support built into SWS. By default SWS builds with support for Gzip, Deflate, Brotli and Zstandard algorithms.

MIME types compressed¶

Compression is only applied to files with the MIME types listed below, indicating text and similarly well compressing formats. The asterisk * is a placeholder indicating an arbitrary MIME type part.

text/*
*+xml
*+json
application/rtf
application/javascript
application/json
application/xml
font/ttf
application/font-sfnt
application/vnd.ms-fontobject
application/wasm

Compression level¶

SWS allows selecting the compression level via --compression-level command line option or the equivalent SERVER_COMPRESSION_LEVEL env. The available values are fastest, best and default. fastest will result in the lowest CPU load but also the worst compression factor. best will attempt to compress the data as much as possible (not recommended with Brotli or Zstandard compression, will be very slow). default tries to strike a balance, choosing a compression level where compression factor is already fairly good but the CPU load is still low.