What this check does
It follows a bounded public redirect chain, reads the final response and lists canonical declarations found in its initial HTML. Relative canonical URLs are resolved against the final public URL.
Free technical SEO tool
Canonical Tag Checker
Check the canonical declaration delivered in a page’s initial public HTML.
What this check does not prove
A canonical is a hint, not a guarantee of Google’s selected canonical or ranking outcome. A missing canonical is worth reviewing, not automatically catastrophic.
Canonical is one signal in a wider technical review.
Compare it with index directives, redirects and sitemap discovery before changing a live site.