Free tool
Full Lighthouse analysis for any URL — mobile and desktop scores, Core Web Vitals field data from real Chrome users, and top performance opportunities. Takes 20–30 seconds.
Up to 5 checks per 24 hours · Results are shareable · No sign-up required
Indirectly, and more than people expect. Engines that fetch pages live work under a timeout — a page that is slow to return HTML can simply be skipped in favour of a faster source that answers the same question. Speed is not a ranking signal for answer engines the way it is for Google, but it does decide whether your content is retrieved at all when the engine is composing an answer under time pressure.
It runs the same Lighthouse analysis for mobile and desktop, then adds the checks that matter specifically for answer engines: whether GPTBot, ClaudeBot, PerplexityBot and Google-Extended are allowed in robots.txt, whether an llms.txt file exists, and how much of your content is present in the raw HTML rather than only after JavaScript runs.
Many AI crawlers do not execute JavaScript. If your copy is rendered client-side, a bot can fetch the page successfully and still see an almost empty document, which means there is nothing to quote. Checking what exists in the server response — before any script runs — tells you whether engines are reading your real content or an empty shell.
Google's Lighthouse mobile run simulates a throttled CPU and a slow connection, and that simulation intermittently errors out on Google's side. The tool retries mobile automatically before giving up, and reports a result whenever either strategy succeeds, so a partial report is normal rather than a sign that something is wrong with your site.
Results are cached per URL for 24 hours, so re-running the same domain inside that window returns the stored report. Anonymous visitors get a small number of checks per day per IP; signed-in accounts get a higher daily allowance that scales with plan, plus a limited number of forced re-analyses that bypass the cache.