Free Canonical Tag Checker — Validate rel=canonical
Canonical Tag Checker
A canonical tag checker inspects a page's <head> for the rel="canonical" link element and flags the errors that stop it from working: missing canonicals, relative rather than absolute URLs, multiple conflicting canonical tags, a canonical pointing cross-domain when it shouldn't, and a canonical that contradicts a noindex directive on the same page. Google treats canonical as a strong hint rather than a directive, so a broken one is often the reason the wrong URL version ranks. Paste a URL or raw HTML below to run the check.
Paste a URL or page HTML to check its canonical tag for missing, relative, multiple or conflicting rel=canonical issues. Free, instant, no signup.
Paste a URL or the page's raw HTML
Enter a live URL to have the tool fetch and parse the head, or paste HTML directly if the page sits behind authentication or you're checking a staging build before launch.
Tool parses every rel=canonical instance
It checks for zero, one, or multiple canonical tags, resolves relative URLs against the page's base, and compares the canonical target against the page's own URL and any noindex or hreflang tags present.
Review the flags and fix at source
Each issue links to the specific problem — for example 'multiple canonicals found, Google will pick one arbitrarily' — so you can go straight to the template or plugin generating the conflicting tag.
Frequently asked questions
What happens if a page has no canonical tag?
Google will still choose a canonical URL for it automatically, using signals like internal linking, redirects and duplicate content clustering — but it may not pick the version you'd choose. Setting an explicit self-referencing canonical on every indexable page removes that ambiguity.
Can a canonical tag point to a different domain?
Yes, cross-domain canonicals are valid and used when the same content is syndicated or hosted on a partner domain, telling Google which domain should rank. It's only an error when it happens unintentionally, usually from a copied template or a staging-to-production migration mistake.
Is a canonical tag a redirect?
No. A canonical tag is a hint that both URLs stay accessible to users, while a redirect actually sends visitors and crawlers to a different URL. Use a canonical for near-duplicate content you want to keep live, and a 301 redirect when the old URL should stop existing entirely.
What happens if a page has both a canonical and a noindex tag pointing elsewhere?
That's a direct conflict: noindex tells Google to drop the page from the index, while a canonical to another URL asks Google to consolidate ranking signals into that other page instead. Google's behaviour here is inconsistent, so this combination should be treated as a bug and fixed rather than relied on.