Free canonical tag checker
Traffic on a page slides for weeks. The content is fine, the links are fine, and the canonical was quietly pointing at another URL the whole time. Paste a URL and see its canonical tag, whether the page points to itself or hands its ranking elsewhere, and the mistakes that drop pages from Google. No signup.
Free, anonymous. Up to 10 checks per hour. We fetch the page once, server-side.
What to check
View the canonical tag
This is one page at one moment. Canonicals break on deploys and CMS updates, and nothing tells you when. See how LinkGuard watches your pages and backlinks.
What this tool checks
It fetches the URL once, server-side, and reads the canonical from both places Google honors:
the HTML <link rel="canonical"> tag and the HTTP Link header.
Then it tells you, in plain terms, what that canonical is doing.
- The verdict — self-referencing, pointing to another URL, missing, or conflicting.
- The canonical URL it declares, resolved to an absolute address, next to the page's own final URL.
- HTML and header, both read, with a flag if they disagree.
- Common mistakes: relative canonicals, more than one tag, canonical to a different host, and canonical combined with noindex.
How to use it
- Paste the exact page URL you want to check, not just the domain. The canonical is per page.
- Read the verdict. Self-referencing is the healthy default; "points to another URL" is the one to look at twice.
- Compare the two URLs. We show the declared canonical next to the page's own URL so a mismatch is obvious.
- Fix and re-check. Edit the tag, redeploy, run it again.
Why the canonical tag is worth checking
The canonical tag decides which URL gets to exist in Google's eyes when the same content sits at more than one address. Get it right and duplicates stop competing; the ranking signals pool onto one strong URL. Get it wrong and you can hand a page's entire ranking to a URL you never meant to promote, with no error, no warning, and no obvious symptom until traffic slides.
The mistakes that do the damage
Two patterns cause most of the damage. The first is the template bug: a canonical that hardcodes the homepage, so every page on the site tells Google "index the homepage instead of me," and the whole site collapses to one URL. The second is the staging leak: a canonical pointing at the staging domain ships to production, so live pages canonicalize to URLs Google can't even reach. Both look normal in a browser. You only see them if you read the tag.
A canonical is a hint, not a command
Google treats rel=canonical as a strong suggestion, not a directive. It weighs
your declared canonical against redirects, internal links, sitemaps, and the content itself,
and it can choose a different canonical than the one you set. When it does, Search Console says
"Duplicate, Google chose different canonical." So a clean self-referencing canonical is
necessary but not sufficient: the rest of your signals have to agree with it. This tool shows
you the signal you control; it can't promise Google will obey it.
Canonical is not a redirect, and not noindex
A canonical does not move the user or the crawler anywhere; the page still loads at its own URL.
If you want a page to actually move, use a 301 redirect. If you want it gone from search, use
noindex. Mixing canonical with noindex sends Google two contradictory instructions
at once, and it may honor neither cleanly. Match the tool to the goal.
Frequently asked questions
What is a canonical tag?
A canonical tag (rel=canonical) tells search engines which URL is the master version of a page when the same or very similar content is reachable at more than one URL. It lives in the HTML head as <link rel="canonical" href="..."> or in the HTTP Link header. It consolidates ranking signals onto the chosen URL, so duplicates do not compete with each other.
What is a self-referencing canonical?
A self-referencing canonical is when a page's canonical points to its own URL. It is the healthy default for any page that should rank on its own: it tells Google "this URL is the original, index this one". This tool reports whether your page is self-referencing by comparing the canonical to the page's own final URL.
Does every page need a canonical tag?
Not strictly. If a page has no canonical, Google chooses one for it, usually the URL it crawled. But a self-referencing canonical is recommended because it removes the guesswork, especially on sites where the same content is reachable with tracking parameters, trailing slashes, or http and https variants. The risk is not missing canonicals; it is wrong ones.
What happens if the canonical points to the wrong URL?
You can de-index the page without realizing it. A canonical pointing to a different URL tells Google to index that other URL instead and to move this page's ranking signals there. The classic disaster is a template bug that canonicalizes every page to the homepage, or a staging canonical that points at the staging domain. The page quietly drops out of search while everything looks fine on the surface.
Can I have more than one canonical tag?
You should not. If a page declares two or more conflicting canonical tags, Google ignores all of them and falls back to choosing a canonical itself. This commonly happens when a CMS adds a self-referencing canonical and a plugin or theme adds another. Keep exactly one canonical per page. This tool flags when it finds more than one.
Should the canonical be an absolute or relative URL?
Use an absolute URL: the full https:// address with the host. Google will resolve a relative canonical, but relative URLs are easy to get wrong, especially across staging and production or http and https, and a wrong resolution points the canonical at the wrong place. Absolute is the safe, recommended form. This tool flags relative canonicals.
What is the difference between canonical and noindex?
They do opposite things. noindex tells Google to drop a page from the index entirely. A canonical tells Google to keep one URL and consolidate duplicates onto it. Putting both on the same page is a contradiction: noindex says "remove this", canonical says "this is the version to keep". Google may ignore the canonical in that case. Pick the one that matches your goal. This tool flags pages that carry both.
Why is my page not indexed even though it has a canonical?
A canonical is a hint, not a command. Google considers it alongside other signals (redirects, internal links, sitemaps, the actual content) and can pick a different canonical than the one you declared, which then shows up in Search Console as "Alternate page with proper canonical tag" or "Duplicate, Google chose different canonical". If the page should rank on its own, make the canonical self-referencing, keep the content unique, and make sure redirects and internal links agree.
Last updated: 2026-05-25