Free Online Canonical Tag Checker

1. Paste the page's HTML into the input box.
2. Read the result banner: it tells you if the canonical is missing, duplicated, relative or valid.
3. Confirm the listed href is an absolute https:// URL pointing to the intended page.
4. If multiple canonicals appear, remove all but the correct one from your template.
5. Re-paste after editing to verify exactly one absolute canonical is present.

A canonical tag — <link rel="canonical" href="..."> in the page head — tells search engines which URL is the preferred, authoritative version of a page when the same or very similar content is reachable at multiple URLs (think tracking parameters, http vs https, trailing slashes, or print versions). Specifying a canonical consolidates ranking signals onto one URL and prevents duplicate-content dilution. Google recommends using absolute URLs (with the full https:// and domain); relative canonicals can be misinterpreted.

This checker parses the HTML you paste and reports one of four outcomes: no canonical tag found, exactly one valid absolute canonical, a relative-URL warning, or multiple conflicting canonical tags (a page should declare only one — several tags may all be ignored). It shows the actual href values it found so you can verify the target is correct and self-referential where intended.

The check is entirely client-side and reads pasted source, so it works for staging URLs and pages behind authentication. Use it whenever you suspect duplicate-content issues or want to confirm a template outputs exactly one correct canonical per page.