Canonical Tag Test
The Canonical Tag Checker reads the rel="canonical" link element in your <head> (and the equivalent HTTP Link header) on any URL, then validates whether the canonical points to a real, indexable page on the same domain.
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- Pass / fail + fix guidance
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The Canonical Tag Checker reads the rel="canonical" link element in your <head> (and the equivalent HTTP Link header) on any URL, then validates whether the canonical points to a real, indexable page on the same domain. We catch the four most common canonical mistakes — missing tag, self-referencing typo, cross-domain mismatch, and conflicting canonical-vs-redirect chains — that quietly cause Google to ignore your preferred URL and split ranking signals across duplicate paths.
What This Tool Checks
- Canonical link tag present in <head>
- HTTP Link: rel="canonical" header (alternative method)
- Self-referencing canonical correctness
- Canonical points to an HTTP 200 URL (not a redirect or 404)
- Cross-domain canonicals (intentional vs. accidental)
- Conflicting canonical between desktop and mobile versions
- Canonical declared on noindex pages (signal conflict)
Why It Matters for SEO
Canonicalization is how you tell Google which URL is the master copy when the same or near-identical content is reachable through multiple paths — with/without trailing slash, with tracking parameters, on print versions, on AMP pages, on category-filter combinations. Without a canonical tag Google picks one for you, often wrong, and ranking power gets fragmented across duplicate URLs. A correct canonical consolidates link equity onto your preferred URL and stops crawl budget being spent on duplicates.
How to Fix It
Add exactly one <link rel="canonical" href="https://yourdomain.com/exact-page-url" /> to every page <head> with the absolute URL of the preferred version. Self-reference on the canonical version itself. Make sure the canonical, redirects and the sitemap all agree. Remove canonical tags from noindex pages.
How It Works
We fetch the URL, parse all <link rel="canonical"> elements and Link headers, follow each canonical target with a HEAD request to confirm the destination is live and indexable, and compare the declared canonical against the URL the user actually requested. Conflicts are surfaced with a clear explanation of which signal Google will respect.
Common Mistakes to Avoid
- No canonical tag at all (Google guesses, often wrong)
- Canonical points to a 404 or a redirected URL
- Canonical uses a relative path instead of absolute URL
- Multiple canonical tags in the same <head> (Google ignores all of them)
- Canonical disagrees with the sitemap, the redirect chain, or hreflang
Quick Checklist
- Exactly one canonical tag per page
- Canonical uses an absolute HTTPS URL
- Canonical target returns HTTP 200
- Canonical agrees with the sitemap
- No canonical on noindex pages
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Use one on every important page. It either self-references (confirming this URL is the master) or points to the canonical alternative when the page is a duplicate / variant. The signal removes ambiguity for Google.
Google chooses a canonical itself, often by signals like internal linking and HTTPS usage. The choice may not be the URL you want indexed, and ranking power can get split across duplicate URLs.
Yes. Cross-domain canonicals are valid and useful when content is republished (e.g. on Medium pointing back to your own site). Use them deliberately and consistently.
Yes — every page should have a canonical that either self-references or points to a clear master version. Self-referencing canonicals act as protection against accidental parameter-based duplicates.
No. Google treats it as a strong hint, not a directive. If your other signals (internal links, sitemap, redirects) point at a different URL as the master, Google may override the canonical.