Performance · 15 points
Text compression
One check, stated three ways: what we measure, what would make it wrong, and how to confirm it yourself.
What this measures
The Content-Encoding header on the HTML response itself: br, gzip, zstd or deflate passes. When no header is present but Content-Length is smaller than the decoded body, that counts too — something compressed it on the way. Pages under 14 KB pass regardless, because at that size compression does not pay for itself.
Where this check can be wrong
Some CDNs compress only for browser User-Agents and serve our crawler identity uncompressed, which would make a correctly configured site look raw. When neither the header nor Content-Length survives the trip, the check says so and takes half the points rather than failing. curl with --compressed to compare.
Verify it without taking our word for it
curl -sI -H 'Accept-Encoding: br,gzip' https://your.site | grep -i content-encoding