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Canonical tag checker

Find the canonical URL a page declares and check whether it points to the page itself, to another URL on the site or to a different host.

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What the canonical checker reads

The rel=canonical link in the page head, resolved to a full URL and compared with the page it was found on, after redirects.

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Canonical mistakes that cost rankings

A canonical that points to a staging host, to the http:// version, or to the home page from every URL tells search engines to index a page you did not mean.

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A check tells you today. Monitoring tells you the day it changes

This is a one-time result. The Indexability option on a website monitor reads the canonical tag on every check and sends a notice when it starts pointing somewhere else.

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Guides

Related checkers

Know when a canonical starts pointing somewhere else See SEO monitoring

Key takeaways

  • This tool loads the page you enter once, follows redirects and reads the rel=canonical link in the HTML as served.
  • It resolves the canonical to a full URL and reports whether it points to the page itself, to another URL on the same host, to the http:// version or to a different host.
  • The same result shows the page's noindex directives and whether robots.txt allows the URL for all crawlers.
  • It is free, needs no login and no credit card.
  • For continuous checks, the Indexability option on a website monitor reads the canonical tag on every check and sends a notice when it changes.

Frequently asked questions.

A canonical tag is a <link rel="canonical" href="https://example.com/page"> element in the page head that names the preferred URL for content reachable at several addresses - with and without a trailing slash, with tracking parameters, over http and https. Search engines use it to pick one URL to index and consolidate the duplicates into it. Google treats it as a strong signal but a hint, not a rule: it can choose a different canonical, and a redirect is a stronger signal. More in what a canonical URL is.
Enter the page address above. The checker loads the page once, follows redirects and reads the rel=canonical link in the HTML as served. It resolves a relative href to a full URL, compares it with the URL the request landed on and reports "Self-referencing", "Points to another URL", "Points to an http:// URL", "Points to another host" or "No canonical tag", along with the number of hreflang alternates. By hand, view the page source and search for rel="canonical".
The canonical tag names the page's own URL. That is the normal setup for a page you want to rank, and Google recommends a self-referential canonical on the canonical page itself. It tells search engines which variant to keep when the same page is also reached with tracking parameters, a different letter case or a trailing slash. The checker reports "Self-referencing" when the canonical resolves to the same URL the check landed on after redirects.
Yes. Google has supported cross-domain canonicals since 2009, for example when the same article lives on two of your own sites. It is still a hint, the other domain's URL may then be shown instead of yours, and for a permanent move a 301 redirect is the stronger signal. Google does not recommend canonicals for content you syndicate to partners. An unexpected other host, often a staging or old domain, is a serious mistake: the checker flags it as "Points to another host", and the guide to fixing a canonical that points to staging covers the fix.
Because it is a hint. Google weighs it against other signals and may pick another URL when they disagree: a redirect to a different version, a sitemap that lists another URL, http and https versions both live, or pages whose content is not really the same. The tag also counts only in the HTML head, and two different canonical tags on one page can give unexpected results. The URL Inspection tool in Search Console shows the canonical Google selected; compare it with what this checker reports.
Absolute. Google's documentation recommends absolute rather than relative paths in rel=canonical. A relative value is resolved against the address of the page it sits on, so the same template served on a staging host or over http produces a different canonical. The checker shows both forms - the href as written and, under "Resolves to", the full URL it becomes - so you can see where a relative value really points.
Yes. /page and /page/ are two different URLs, and a canonical that differs from the page only by the slash names the other one as the version to index. The checker flags this case as "Points to a slightly different URL". Pick one form, use it in the canonical, in internal links and in the sitemap, and redirect the other form to it.
Nothing breaks: search engines pick the preferred URL themselves. The risk is that signals split between variants of the same page - with and without a trailing slash, or with tracking parameters - and that the version chosen is not the one you wanted. The checker shows "No canonical tag" in amber. Adding a self-referencing canonical to every page you want indexed is the usual fix, and the one Google recommends.
Avoid it on the same page. A self-referencing canonical says index this URL while noindex says do not, and Google advises against using noindex to control which URL becomes canonical within a site; it also says not to use robots.txt for canonicalization. To merge duplicates, point their canonical at the preferred URL and keep them crawlable. The result shows the page's noindex next to its canonical, and the noindex checker shows where a noindex comes from.
No. It reads the first rel=canonical link in the HTML as the server sends it, without running JavaScript, so a canonical that a script adds is not seen. Google says a script may set a canonical that the HTML leaves out but should not change it to a different URL, and it must be the only canonical tag on the page. Google also accepts a canonical in the HTTP Link header, such as Link: <https://example.com/file.pdf>; rel="canonical", common for PDFs; this checker does not read that header yet.

Part of HostTracker's website monitoring software.