Canonical checker: see which URL a page asks to be indexed as.

Enter a page URL. The tool fetches it, reads the canonical link tag, tells you whether it points to the page itself or to another URL, and checks that the target it names actually resolves.

By · Updated September 25, 2026

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Canonical tag checker

Runs on our server, which fetches the public URL you enter. We count runs and never save what you enter; an identical request may be answered from memory for up to five minutes.

What you can do with it

  • Find out why Google indexes a different URL from the one you expected
  • Catch a canonical that points at a redirect, a 404 or the staging host
  • Check that filtered or tracked URLs point back to the clean version
  • Confirm a migration updated canonicals to the new domain

How it works, step by step

  1. 1

    Decide which URL should be indexed

    Before you check anything, write down the one URL you want in search results for this content: protocol, host, path and trailing slash exactly as you want them. Every other version should point there.

  2. 2

    Read the declared canonical

    Find the link rel=canonical tag in the page's head. On the preferred URL it should point to itself. On a duplicate, such as a URL with tracking parameters, it should point to the preferred URL.

  3. 3

    Check that the target resolves

    The URL in the canonical should return a 200 directly. If it redirects, returns a 404 or is blocked, you are asking search engines to prefer a page that does not work, and they will likely ignore the hint.

  4. 4

    Make the other signals agree

    Internal links, the sitemap, hreflang and redirects should all name the same preferred URL. A canonical that disagrees with everything else is the one Google is most likely to override.

  5. 5

    Recheck after template changes

    Canonicals are usually generated by a template or plugin, so one change can alter them across thousands of pages. Test a URL from each template after a release.

What a canonical does

The same content is often reachable at several URLs: with and without www, over http and https, with a trailing slash and without, with ?utm_source= on the end, or under two category paths. Search engines want to index one of them. The rel="canonical" link tag is how a page tells them which one you prefer.

It is a hint, not a command. Google documents it as one signal among several, alongside redirects, internal links and sitemap entries. When they agree, the canonical is usually respected. When they disagree, Google picks for itself.

Common mistakes

  • Canonical to a redirect or a 404. The page asks to be indexed as a URL that does not load. This happens after migrations and slug changes when the template kept the old path.
  • Relative canonicals. href="/pricing" resolves against whatever host served the page. On a staging host or a mirror, every page canonicalizes to that host.
  • http versus https, www versus bare domain. A canonical naming the http or non-preferred host sends search engines to a version that immediately redirects.
  • Trailing slash mismatch. /guide and /guide/ are different URLs. If the site serves one and the canonical names the other, the target is a redirect or a 404.
  • Paginated pages canonicalized to page 1. Page 2 of a list is not a duplicate of page 1; it lists different items. Canonicalizing it to page 1 asks search engines to ignore those items. Each page in a series should usually point to itself.
  • Header and HTML disagree. A server or CDN adds one canonical in the HTTP Link header and the CMS writes another in the HTML. Conflicting canonicals are likely to be ignored.
  • Canonical plus noindex. Pointing to another URL while also saying noindex sends mixed messages. Pick one: consolidate with a canonical, or remove with noindex.

How to read the result

If the canonical points to the page itself and the target resolves, the page is asking to be indexed at the URL you tested. If it points elsewhere, check that this is deliberate: it should only happen on duplicates. If the target does not resolve cleanly, fix the canonical first, since it is sending search engines to a dead end.

What the checker does not do

It reads the canonical from one page’s HTML and checks the target it names. It does not tell you which canonical Google actually chose, crawl other pages on the site, or compare page content to decide whether two URLs are true duplicates. For the rest of the page head, use the website metadata checker.

A clean canonical makes sure the right URL gets the credit. AltoRank plans and drafts the content that earns it every week, and a person approves each piece before it publishes.

Frequently asked questions

What does the checker report?

The canonical URL the page declares in its HTML, whether that URL is the page itself or a different one, and the status of the canonical target when the tool requests it.

Does Google always follow the canonical tag?

No. Google treats rel=canonical as a strong hint, not a directive. It weighs it against redirects, internal links, sitemaps and whether the pages really are duplicates, and it can choose a different canonical. Search Console's URL Inspection shows which one Google picked.

Should every page have a self-referencing canonical?

It is a sensible default. A self-referencing canonical tells search engines the clean URL is the preferred one even when the page is reached with tracking parameters or a different case. It is not required, but it removes guesswork.

Can I use a relative URL in the canonical?

Google accepts relative URLs, but recommends absolute ones. A relative canonical resolves against whatever host served the page, so a staging copy or an alternate domain ends up canonicalizing to itself. Absolute URLs avoid that.

What about canonicals sent in an HTTP header?

A canonical can also be sent in a Link HTTP header, which is the only option for files like PDFs. If a page sends one canonical in the header and a different one in the HTML, the signals conflict and search engines may ignore both. Declare it in one place, or make both identical.

Does it store the URL I check?

No. Our server fetches the public page and its canonical target, returns the result to your browser and keeps only a count of how many times the tool ran that day. There is a daily usage limit so it can stay free without a signup.

More free tools

Free Website Metadata Checker: Title, OG, Schema Enter a URL and see the page's title, meta description, canonical, robots tag, Open Graph and Twitter tags, JSON-LD types, h1 and language. Free XML Sitemap Checker and Validator Enter a site or sitemap URL. The tool finds the sitemap, checks that it parses, counts its URLs and child sitemaps, and flags obvious problems in a sample. Free Link Extractor: Every Link on a Page Enter a URL and get every link in the page's raw HTML, with anchor text, split into internal and external, and any nofollow, sponsored or ugc attributes. Free AI Crawler Simulator: See What GPTBot Sees Fetch any URL as GPTBot, ClaudeBot, PerplexityBot, OAI-SearchBot and Googlebot. See each robots.txt verdict, status code and the text in the raw HTML.
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