Website PageSpeed & Performance Auditor

Website PageSpeed & Performance Auditor fetches a page and reports what its HTML implies about load performance, with separate mobile and desktop profiles, a filmstrip of render milestones, and lists of accessibility, best-practice and SEO checks.

The split between measured and derived is the thing to understand here. Measured from the response: time to first byte, transfer size, and whether gzip or brotli compression is on. Derived from the markup: the number of render-blocking scripts and stylesheets, the DOM node count and depth, and how many images declare no dimensions. Everything labelled FCP, LCP, Speed Index, TBT or CLS is then computed from those inputs using Lighthouse's metric weightings — a model of what the markup predicts rather than a browser measurement, which is why the INP row reads "Field Only" instead of showing a number.

Enter a URL and ShortTrick's server performs the fetch, which means the timing in the report is the latency between our server and yours. The target sees our inspect-route user agent and nothing of yours, at most two megabytes of HTML is read, and the route allows twenty inspections a minute per client. Paste a template's HTML instead and no request leaves anywhere — the right mode for auditing markup that is not deployed yet.

Checking a template for blocking scripts before it ships, confirming compression is enabled at the origin, counting unsized images across a page, and auditing raw HTML that has no URL yet.

Also known as: website speed test · pagespeed checker · core web vitals test