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Canonical tag checker

Enter a page address to see which URL it names as canonical, and whether that URL looks right.

Free, no signup. We fetch the page once, the way your server first sends it, without running JavaScript.

What is a canonical tag?

When the same page can be reached at more than one address, a canonical tag tells search engines which one is the main version. It is a link element in the page's head:

<link rel="canonical" href="https://www.example.co.uk/boiler-repair">

Duplicates happen more often than people think: with and without www, http and https, tracking parameters such as ?utm_source=newsletter, sort and filter options on shop pages, and a product listed in two categories. Without a canonical, Google picks a version itself, and it may not be the one you want in results.

Google treats rel=canonical as a strong signal, not an order. It weighs it alongside redirects, internal links, sitemaps and HTTPS when it chooses, so make those signals agree.

Canonical tag or 301 redirect?

If visitors never need the duplicate address, redirect it (a 301) to the main one: http to https, or non-www to www, for example. Use a canonical tag when both addresses must keep working, such as a page with tracking parameters or a product that sits in two categories.

Common canonical mistakes and how to fix them

  • Every page pointing to the homepage. Often a theme or plugin setting. It tells Google your pages are copies of the homepage. Each page should name itself, or the page it really copies.
  • Pointing to a URL that redirects, errors or is noindexed. Point straight at the final, live, indexable address.
  • Relative URLs. Google supports them but recommends full absolute URLs (starting https://), which can't be misread.
  • More than one canonical. A theme and an SEO plugin can both add one, sometimes with different URLs. Keep one: Google says not to send conflicting canonical signals.
  • A canonical plus noindex. They send opposite messages, and Google advises against using noindex to choose a canonical within a site.
  • A canonical outside the head. Google only accepts rel=canonical in the head. A tag injected lower down the page is ignored.

How to see which canonical Google chose

In Google Search Console, inspect the address with URL Inspection. It shows the “user-declared canonical” (yours) and the “Google-selected canonical”. If they differ, look for the signal pulling the other way: a redirect, internal links to the other version, or a sitemap that lists it.

Canonical tags: common questions

What is a canonical tag?

A link rel="canonical" element in a page’s head that names the main address for that content, so search engines know which version to show when the same page can be reached at several addresses.

Should a page have a canonical tag pointing to itself?

Yes. Google recommends putting a canonical on the canonical page itself (a self-referencing canonical). It protects the page when it is reached with tracking parameters or other variations of its address.

Does Google always use the canonical I set?

No. Google treats it as a strong signal, not an order, and may choose another URL if redirects, internal links or your sitemap point elsewhere. URL Inspection in Search Console shows which one it chose.

Canonical tag or 301 redirect: which should I use?

Redirect when visitors never need the duplicate address, such as old URLs, http to https, or non-www to www. Use a canonical when both addresses must keep working, such as pages with tracking or filter parameters.

Can a page have more than one canonical tag?

It shouldn’t. If a theme and a plugin both add one, especially with different URLs, Google may ignore them. Keep one, in the head, with a full absolute URL.

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