HTML response is not compressed

What this means

This HTML response is served without a Content-Encoding header, meaning it went over the wire uncompressed. Text compresses extremely well — gzip typically removes around 70% of an HTML payload and Brotli more — so every visitor is paying for bytes that cost almost nothing to eliminate.

How to fix it

Enable Brotli (or at minimum gzip) for text/html, text/css, application/javascript and application/json at the server or CDN edge. Nearly every host exposes this as a one-line setting.

Fix effort

This check needs a developer fix: it turns on a routing, hosting or infrastructure decision that no automatic edit can make safely.

Authoritative source

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Encoding