Free tool · No sign-up
Canonical tag checker
Updated 2 November 2026
Enter a URL to see its rel=canonical tag and HTTP Link header, whether it points to itself or another page, and the conflicts that make Google ignore it: several canonicals, http on an https site, a different host, or noindex on the same page.
Want every page checked, not just this one? See the full audit →
What a canonical tag does
The same content often lives at several addresses: with and without www, with tracking parameters, sorted or filtered versions of a list, or printer-friendly copies. A canonical tag, <link rel="canonical" href="https://example.com/page"> in the head, tells search engines which address you prefer. Google treats it as a strong hint, not an order, and combines it with redirects, internal links and sitemaps to choose the URL it shows.
What this checker flags
- Missing canonical. Not an error, but a self-referencing canonical on every indexable page protects you from parameter and case variants.
- More than one canonical. When a theme and a plugin both add one, Google may ignore all of them.
- Relative URLs. Allowed, but easy to break on staging copies and mirrors. Use the full https address.
- http:// canonical on an https:// page, or a different host (www versus non-www). Both send mixed signals.
- noindex plus canonical. One says "index that other URL", the other says "drop this". Pick one.
- Redirects. Your canonical, internal links and sitemap should all point at the final URL, not one that redirects.
- og:url mismatch. Keeping og:url equal to the canonical keeps social shares counted against one URL.
When a canonical to another page is right
Point the canonical elsewhere only when this page is a near-duplicate: a URL with tracking or sort parameters, a syndicated copy of an article, or a product variant you don't want ranking on its own. Pages that should rank by themselves, such as page 2 of a category or a distinct product, should canonicalise to themselves.
Canonicals in headers
For PDFs and other non-HTML files you can send Link: <https://example.com/file.pdf>; rel="canonical" as an HTTP header. This checker reports that header too.
Frequently asked questions
Should every page have a self-referencing canonical?
It's good practice for indexable pages. It costs nothing and stops variants with parameters, uppercase letters or trailing slashes from competing with the main URL.
Is a canonical the same as a 301 redirect?
No. A redirect moves visitors and crawlers to the new URL. A canonical keeps both URLs working for people and only suggests which one to index.
Why does Google choose a different canonical from mine?
Google weighs your tag against redirects, internal links, sitemaps, HTTPS and content similarity. If those disagree, it may pick another URL. Make every signal point to the same address.
Can I canonicalise to another domain?
Yes, for syndicated content. Make sure the other page really has the same content and is indexable.