Check any page's canonical tag.

Enter a URL to see its rel=canonical from the HTML and HTTP headers, the redirects in front of it, and whether the canonical target is live and indexable. Free, no sign-up.

HTML + Link headerRedirect chainTests the target URLNo sign-up

Reads the page's raw HTML and headers, without running JavaScript.

Why use it

One wrong canonical can hide a page from Google.

The canonical tag tells search engines which URL is the main version of a page. Point it at the wrong place and the page you wanted to rank can drop out of the index.

Catches conflicting signals

Two different canonicals, a canonical in the body, a canonical plus noindex: the mistakes that make Google ignore your choice and pick its own.

Tests the target, not just the tag

It fetches the canonical URL too, so you learn whether it returns 200, redirects, is noindexed, or points somewhere else again.

Shows the redirect path

Every hop from the address you entered to the final page is listed, with its status code, so http to https and www rules are easy to check.

How it works

A URL in, a canonical verdict out.

Three requests at most: the page, its redirects and the canonical target.

  1. 1

    Enter a URL

    Paste any public page address, including query parameters if you want to test a variant.

  2. 2

    It follows the trail

    It follows redirects, reads rel=canonical from the HTML head and the Link header, then fetches the target.

  3. 3

    Review the findings

    Each issue comes with what it means and how to fix it in your CMS or SEO plugin.

Guide

Canonical tags, explained properly.

What a canonical does, when to use one, and the mistakes this checker looks for.

What is a canonical tag?

A canonical tag is a line of HTML in a page's head, <link rel="canonical" href="https://example.com/page">, that names the preferred URL for that content. When the same page is reachable at several addresses (with tracking parameters, with and without www, sorted or filtered), the canonical tells search engines which one to index and credit.

Google treats it as a strong hint, not a rule. It weighs the tag together with redirects, internal links, sitemaps and HTTPS, and can choose a different canonical if your signals disagree.

Should every page have a self-referencing canonical?

It's good practice. A canonical pointing to the page's own clean URL protects it against duplicates you didn't create, such as links with UTM parameters or session IDs, and most SEO plugins add one by default.

Point a canonical somewhere else only when the page really is a duplicate or a variant of another page, like a print version or a product shown under several category paths.

Common canonical tag mistakes

These are the problems the checker flags.

  • More than one canonical with different URLs, so Google may ignore them all
  • A canonical inside the <body>, which Google doesn't read
  • A canonical pointing at a page that redirects, returns 404 or is noindex
  • Canonical chains, where page A points to B and B points to C
  • noindex and a canonical to another URL on the same page
  • http or non-www canonicals on an https, www site
  • Every page on a site canonicalised to the homepage

Canonical vs 301 redirect

A 301 redirect sends people and crawlers to another URL, and the old one stops being viewable. A canonical keeps both URLs working for visitors and only tells search engines which one to index.

Use a redirect when the old URL shouldn't exist any more, such as after a move or a merge. Use a canonical when both versions need to stay, such as filtered product lists or syndicated copies.

Canonical vs noindex

noindex says drop this page from search. A canonical to another URL says this page is a copy, so give its signals to that one. Google advises against combining them on the same page because the messages conflict. If a page is a duplicate, use the canonical. If it should never appear in search, use noindex.

Canonicals in HTTP headers

For files that can't hold HTML tags, such as PDFs, a canonical can be sent as an HTTP header: Link: <https://example.com/guide>; rel="canonical". The checker reads the header as well as the HTML. Use one method per URL, not both with different values.

How to see which canonical Google chose

This checker shows what your page declares. Google may pick a different URL. To see Google's choice, open Google Search Console, run URL Inspection on the page, and compare "User-declared canonical" with "Google-selected canonical". If they differ, make your signals agree: the canonical, internal links, sitemap URLs and redirects should all point at the same address.

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It tracks whether ChatGPT, Perplexity, Gemini, Claude, Google AI Overview and Google AI Mode recommend you, rechecked throughout the week.

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Canonical Tag Checker, answered.

What it does, what it runs on, and how it fits the platform.

See the full platform →

It fetches a page, follows any redirects, reads rel=canonical from the HTML head and the HTTP Link header, then fetches the canonical URL to confirm it's live, not redirecting, not noindex and not canonicalising somewhere else.

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