Canonical URL Checker & Validator

What this tool does

Enter a URL and the tool reads the canonical declarations on the page, both <link rel="canonical"> tags in the HTML and a canonical in the HTTP Link header, and tells you what it found: no canonical, a self-referencing one, one pointing to another page or domain, or several that conflict.

What a canonical is for

When the same content is reachable at several URLs (with and without www, with tracking parameters, with a trailing slash, in a print version), the canonical tag tells search engines which one you prefer. It is a strong hint, not a command, and Google may choose a different URL if signals disagree.

What the results mean

• Self-referencing canonical. The usual healthy setup: the page names itself.
• No canonical. Not fatal, but search engines will pick for themselves. Adding a self-referencing one is a good habit.
• Points to another URL on the same site. Fine if you intend the page to be a duplicate. Wrong if you copied a template and the canonical still points to the template’s source.
• Points to another domain. You are telling search engines the content belongs elsewhere. Correct for syndicated content, harmful if it’s an accident.
• More than one canonical. The tool warns that search engines ignore the tags when they conflict. This often happens when a theme and an SEO plugin both add one.

Limits

The tool reads the HTML your server returns. A canonical inserted by JavaScript after load won’t be detected. It also doesn’t check that the target URL returns a 200, so run the target through the HTTP status checker if you are unsure.

Results are cached for 10 minutes. Up to 15 checks a minute are allowed.