Canonical Tag Checker

What the Canonical Tag Checker checks

A canonical tag, <link rel="canonical" href="…"> in the head of a page, names the preferred URL of that content. When the same page can be reached under several addresses, with tracking parameters, with and without www, over HTTP and HTTPS, it tells search engines which one to index and credit with links.

This checker requests the URL you enter and reads its canonical tag. It checks that one is present, that it is an absolute URL on the same host and on HTTPS, and whether it points to the page itself or to another URL. It compares og:url with the canonical, looks for noindex in the meta robots tag or the X-Robots-Tag header, and reports the redirect chain to the page. It also requests the other host variant once, www or the bare domain, to see whether it redirects to yours or serves a second copy.

Why it matters

Duplicate URLs split signals. Links, shares and crawl attention spread over several addresses, and search engines have to guess which one to show. Google treats the canonical as a strong hint, not a directive: it weighs it against redirects, internal links and sitemaps, and may choose a different URL when those signals disagree.

Contradictions are the usual problem. A canonical on a noindex page sends two opposite messages. A canonical pointing to a URL that redirects, or to the HTTP version, points at an address that is not the final one. A relative or malformed canonical can be misread, and two canonical tags on one page are typically both ignored. Our guide to canonical URLs explains how Google resolves these cases.

How to fix common problems

Give every indexable page a self-referencing canonical with its full absolute address, for example https://www.example.com/page. Point duplicates, such as parameter or print versions, at the main version. Make sure there is only one canonical tag, and that a plugin or theme does not add a second.

The target must be a page you want indexed: it should answer 200, without a redirect and without noindex. If a page should stay out of the index, use noindex alone and drop the canonical to another URL. Keep og:url equal to the canonical so shares collect under one address.

Pick one host and redirect the other to it with a 301, as described in www vs non-www, and keep redirect chains to a single hop. Then use the same canonical address in internal links and in your sitemap, so all signals agree. The full PerfoMetrix audit checks the canonical next to the sitemap, hreflang and the rest of the page.

Questions

Does Google always follow the canonical tag?

No. It is a strong hint. Google may pick another URL if redirects, internal links or the sitemap point elsewhere, or if the pages are not really duplicates. The URL Inspection tool in Search Console shows which canonical Google selected.

Should a page have a canonical that points to itself?

Yes. A self-referencing canonical is recommended: it settles which URL is preferred when the page is also reached with parameters or under another host.

Can I combine canonical and noindex?

Avoid it. noindex asks for the page to be dropped, while a canonical to another URL says it is a duplicate to be consolidated. Choose one, depending on what you want.

Can the canonical be a relative URL?

Google accepts relative URLs, but absolute URLs are safer: a relative path resolves against whatever host and protocol the page was fetched from, which is exactly what the canonical is meant to settle.