crowsite/libs/crow/docs/guides/compression.md

:octicons-feed-tag-16: v0.3

Crow supports Zlib compression using Gzip or Deflate algorithms.

HTTP Compression

HTTP compression is by default disabled in crow. Do the following to enable it:

• Define CROW_ENABLE_COMPRESSION in your compiler definitions (g++ main.cpp -DCROW_ENABLE_COMPRESSION for example) or set(CROW_FEATURES compression) in CMakeLists.txt.
• Call #!cpp use_compression(crow::compression::algorithm) on your Crow app.
• When compiling your application, make sure that ZLIB is included as a dependency. Either through -lz compiler argument or find_package(ZLIB) in CMake.

!!! note

3<sup>rd</sup> point is not needed for MSVC or CMake projects using `Crow::Crow` since `vcpkg.json` and Crow's target already include zlib as a dependency.

For the compression algorithm you can use crow::compression::algorithm::DEFLATE or crow::compression::algorithm::GZIP.
And now your HTTP responses will be compressed.

Websocket Compression

Crow currently does not support Websocket compression.
Feel free to discuss the subject with us on GitHub if you're feeling adventurous and want to try to implement it. We appreciate all the help.