Healthy page
- Input
- https://example.com/blog/post
- Output
- Canonical matches the final URL — self-referencing
This is what most pages should look like. The canonical points at itself, so there is no ambiguity about which URL to index.
Canonical Tag Checker
A canonical tag tells search engines which URL is the preferred version of a page when the same content is reachable at several addresses. This checker fetches a live page, finds its canonical tag, follows any redirects, and reports whether the tag points back at the page itself. Paste a URL to see exactly what a crawler sees.
Runs entirely in your browser — nothing you type is uploaded.
How to
How to use the Canonical Tag Checker
- 1
Paste the URL
Enter the full address of a public page, including https://.
- 2
Run the check
The page is fetched server-side with a real user agent, following any redirects along the way.
- 3
Read the result
You get the canonical URL found, the final URL after redirects, the status code, and whether the two agree.
- 4
Fix what it flags
A missing, relative or mismatched canonical is reported with what to change.
Examples
Canonical Tag Checker examples
Redirect changes the URL
- Input
- http://example.com/page (redirects to https)
- Output
- Final URL https://example.com/page · canonical agrees
The checker follows redirects and compares the canonical against the final URL, not the one you typed.
Relative canonical
- Input
- <link rel="canonical" href="/page" />
- Output
- Resolved to https://example.com/page
Relative canonicals are valid but easy to get wrong. The tool resolves them against the page URL so you can see what Google would.
Why use it
What the Canonical Tag Checker gives you
Sees what a crawler sees
The page is fetched server-side rather than read from your browser, so the result reflects what a search engine receives.
Redirects followed and reported
You find out when the URL you entered is not the URL that finally served the page, which is where most canonical confusion starts.
Relative URLs resolved
A canonical of /page is resolved to its absolute form, so comparisons are meaningful instead of always failing.
Trailing slashes handled
URLs are compared after normalising trailing slashes and default ports, so cosmetic differences are not reported as mismatches.
Free with no account
Check any public page. Requests are rate limited to keep the service available for everyone.
Good to know
Canonical Tag Checker limitations
- Only public pages can be checked. Anything behind a login, a firewall or an aggressive bot filter will fail to fetch.
- Canonicals injected by JavaScript after load are not seen, because only the served HTML is read. Google may still process them.
- Only the first 100 KB of HTML is read, which covers the head on virtually every page but could miss a canonical placed unusually late.
- A canonical is a hint, not an instruction. Google can and does ignore one it disagrees with.
Summary
Canonical Tag Checker in short
- A canonical tag names the preferred URL when the same content sits at several addresses.
- Most pages should have a self-referencing canonical pointing at their own final URL.
- Canonicals are compared against the URL after redirects, not the one you typed.
- Google treats canonicals as a hint and may choose a different URL.
FAQ
Canonical Tag Checker questions
What is a canonical tag?
A canonical tag is a link element in a page's head naming the preferred URL for that content. It exists so that when the same page is reachable at several addresses, search engines know which one to index and credit.
Should every page point at itself?
Yes, in almost all cases. A self-referencing canonical removes ambiguity and protects against duplicate URLs created by tracking parameters or trailing-slash variations. Point elsewhere only when the page really is a duplicate of another.
What happens if a page has no canonical tag?
Google picks a canonical itself, based on internal links, sitemaps and redirects. It often chooses correctly, but you have no control — and on sites with parameters or pagination it frequently chooses wrong.
Can a canonical URL be relative?
It is technically valid, but absolute URLs are strongly recommended. A relative canonical resolves against the page's base URL, and any confusion there points the canonical somewhere unintended.
Why does the final URL differ from the one I entered?
The page redirected — commonly http to https, or a non-www to www version. The canonical should match the final URL, since that is the one actually serving the content.
Why is Google indexing a different URL than my canonical?
Canonicals are a hint. If Google sees conflicting signals — internal links, sitemap entries or redirects pointing elsewhere — it may pick its own. Search Console's URL Inspection tool shows which URL it chose and why.
Should I use a canonical or a 301 redirect?
Use a 301 when the old URL should no longer be reachable. Use a canonical when both URLs must stay available — a product in two categories, or a page with tracking parameters — but only one should be indexed.
What if a page has more than one canonical tag?
Google ignores all of them and picks a URL itself. Duplicate canonicals usually come from a theme and a plugin both adding one, so check for a second tag if results look wrong.
Does this detect canonicals added by JavaScript?
No. Only the HTML served by the server is read. Google renders JavaScript and may pick up such a canonical, but relying on that is risky — put the canonical in the initial HTML.
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