IIS Brotli

Google Brotli compression module for Microsoft IIS

Brotli is an open source data compression library from Google, it improves on gzip's compression ratio by roughly 17-25%.

We-Amp B.V. has made Brotli available for Microsoft IIS. The server module gets installed as a native http module.


  • Brotli compression improves on the built-in IIS gzip compression ratio by roughly 17-25%.
  • Brotli -11 density compared to gzip -9:
    HTML (multi-language corpus): 25 % savings
    Javascript (Alexa top 10k): 17 % savings
    Minified js (Alexa top 10k): 17 % savings
    CSS (Alexa top 10k): 20 % savings


  • Brotli encoding is currently only requested by browsers for https requests, to avoid trouble with bad intermediaries (proxies).
  • Dynamically generated content needs it Content-Type header to be set in order te be compressed.

Brotli browser support


  • Firefox: 44+ (on by default)
  • Chrome: 49+ (not by default, but can be enabled)
  • Edge: 15+ (on by default)