Free, no sign-up
Two things you can run on your own site right now. Both give you the real numbers with an explanation attached, and neither asks for an email address before it shows you anything.
Type your domain and see who your registrar is, when it renews, whether it's locked against transfer, and where your DNS and email are answered. About a second.
Reads two of the nine accounts a website depends on. It can't name the owner — registrant details are hidden on almost every domain now — and it can't see anything behind a login.
Runs your page through Google PageSpeed Insights and returns the score, your Core Web Vitals and a ranked list of what to fix, each one explained in plain English.
Takes 20–40 seconds, because it's a real page load on Google's infrastructure. The score is a lab test on a simulated phone; the field data underneath it is what Google actually ranks on.
The usual version of a free tool is a “free audit” you receive after handing over an email address, followed by a phone call you didn't ask for. Your own numbers shouldn't cost you your inbox, so these just run.
If something in a result doesn't make sense, send it to me. You'll get a straight answer about what it means, and that's the whole transaction — there's no mailing list here to add you to.
Both tools came out of questions people actually ask. The domain check is the automated half of who actually owns your website, and the speed test is the reason how to read a PageSpeed report exists. If you'd rather understand the thing than run it, the Learning Center is the long version.