How it works
Paste a public URL and, if you want, a focus phrase. The server fetches the HTML with the same limits as the other URL tools: no localhost, no literal IPs, no private or link-local ranges including 169.254.169.254, a 1.5 MB cap, a short timeout, and no JavaScript. The address is not stored.
The page then reports a checklist: title tag presence and length, meta description (and whether it duplicates og:description), canonical, robots meta, html lang, the H1–H6 outline, images missing alt, internal vs external links with rel=nofollow, sponsored, or ugc, Open Graph title/description/image presence, and JSON-LD @type values. Each row is pass, warn, or note. There is no 0–100 SEO score.
A short example
A product page whose title is 58 characters, that has one H1, a meta description, lang=en, and a BlogPosting JSON-LD block will show mostly pass rows, with a note if og:image is missing. That is a reading of the HTML. It does not mean Google will index the page, show a rich result, or rank the URL.
What this does not decide
This is not a Google audit. It does not run JavaScript, so markup a tag manager injects after load is invisible. It does not crawl the rest of the site, render CSS, or check whether Googlebot can index the URL. A pass on canonical or robots is not a guarantee of indexation.
Pixel width on the title is an estimate from character count, not the canvas meter in the meta title checker. Use that tool when you care about truncation. Use the heading, schema, and Open Graph checkers when you need the full outline, property list, or card preview.
Specialist tools: meta title checker, heading checker, schema markup checker, and Open Graph checker. The free tools index lists the rest.