Canonical tags point to the page itself. Indexes consolidate signals onto the canonical URL.
The check reads each page's <link rel="canonical"> and compares it to the URL fetched. A canonical that points elsewhere hands the page's standing to another address; a missing one lets duplicate URLs compete.
Indexes consolidate signals onto the canonical URL. A page that says "the real copy is over there" loses its own standing; a page with no canonical can be indexed under several URLs (with and without www, with tracking parameters) that split its weight.
View source, find rel="canonical", and check that it is the same URL you are on — same host, same scheme, same path.
What the agent does: the agent names the page and where its canonical points; the tag lives in your template.
Part of the 23 checks · group: Crawler access — robots.txt, CDN/bot filter, login walls, noindex, HTTP status, sitemap, canonical.
On the syndicated copy, yes. On your own original, it points to itself. The check flags only pages whose canonical points away from the page it was fetched from.
The page check reads your public pages from outside and runs all 22 — free, no signup, no AI engine involved.