Performance · 15 points
Static asset caching
One check, stated three ways: what we measure, what would make it wrong, and how to confirm it yourself.
What this measures
Fetches the first same-origin stylesheet or script the page references and reads its Cache-Control: max-age of a month or more with a hashed filename passes, an hour or a day is partial, no-store or nothing at all fails.
Where this check can be wrong
A site that inlines its CSS and serves no separate asset cannot be measured and is not marked down. Development builds that skip hashing get a low score here even though production may be configured correctly.
Verify it without taking our word for it
DevTools → Network, reload, and read the Cache-Control column on the .css or .js request.