PageSpeed Insights
pagespeed.web.dev
Scores a page on real-user Core Web Vitals and lab measurements
No sign-up
Loading page
webpagetest.org
Loads your page from a chosen city and browser and films the result.
The deep version of a speed test: pick a location, a real browser, a connection profile, and get a waterfall of every request, a filmstrip of the render and a video you can scrub. Repeat-view runs show what your caching headers actually do. It answers 'why is it slow' where a score only tells you that it is. Free tests queue behind everyone else, and reading a waterfall properly is a skill rather than a glance.
AltFTool does this too
If you would rather not leave the site, Web Speed Checker covers the same job here — free, no account, and it runs in your browser.
Open Web Speed CheckerQuestions
Works the moment the page loads. No account, no email, no trial. Free tests sit in a shared queue at busy times, and the results need interpreting rather than reading.
Yes. WebPageTest sends your input to its own servers to process it. That is fine for public material; for anything containing personal data, use one of the on-device tools instead.
Free tests sit in a shared queue at busy times, and the results need interpreting rather than reading.
Alternatives
Same category or same task, ordered by how closely they overlap.
pagespeed.web.dev
Scores a page on real-user Core Web Vitals and lab measurements
ssllabs.com
Grades a site's TLS configuration from A+ down to F and says why
securityheaders.com
Grades the HTTP security headers a site sends and names the missing ones
wave.webaim.org
Overlays accessibility errors directly on top of the page they affect
downforeveryoneorjustme.com
Settles whether a site is actually down or only down for you
lookup.icann.org
The registry's own WHOIS record for a domain, with no upsell