Stop duplicate URLs competing
The same page is often reachable at several addresses: with and without www, over http and https, with tracking parameters or trailing slashes. A canonical tag (<link rel="canonical">) tells search engines which one to index, consolidating ranking signals onto a single URL.
The checker finds canonical tags in the HTML and in the HTTP Link header, flags multiple or conflicting canonicals, tells you whether the page is self-referencing or pointing elsewhere, and then requests the canonical URL to confirm it returns 200 without redirects — a canonical that redirects or 404s is ignored by Google.
How to check a canonical tag
- 1
Enter the page URL
Try variants like http:// or with parameters too.
- 2
Read the canonical
See where it points.
- 3
Check the target
It must load with 200 OK.
Key features
HTML and header canonicals
Both locations checked.
Conflict detection
Multiple or disagreeing tags flagged.
Target verification
Status and redirects of the canonical URL.
Protocol check
Catches https pages pointing to http.
Common uses
- E-commerce filters: Keep faceted URLs from being indexed separately.
- Site migrations: Confirm canonicals point to the new URLs.
- Syndicated content: Verify the original article is credited.
Tips and good to know
- Use absolute URLs in canonical tags, and keep only one per page.
- A canonical is a strong hint, not a command. Google may choose another URL if signals like internal links and sitemaps disagree.