Canonical Tag Checker
Fetch any URL and verify the canonical tag — detect self-referential and cross-domain canonicals.
Enter a URL above and click Check to fetch the page and extract its canonical tag.
Page is fetched server-side via GET /api/v1/seo/canonical-check to bypass browser CORS restrictions.
About this tool
Canonical Tag Checker fetches a live page and extracts the rel=canonical tag from its HTML <head>. It shows you whether a canonical is present, the canonical URL found, and whether it matches the input URL (self-referential), points to a different URL (cross-domain or cross-path), or is missing entirely. Missing or incorrect canonical tags are a common source of duplicate content issues that split ranking signals between multiple page versions. The check is performed server-side to bypass CORS restrictions.
How to use
- Enter the full URL of the page you want to check.
- Click Check Canonical to fetch and analyse the page.
- Review whether the canonical is self-referential, cross-domain, or missing.
Related Tools
Generate HTML meta tags including OpenGraph and Twitter Card markup.
Build a valid robots.txt file with allow, disallow, and sitemap rules.
Trace the full redirect chain for any URL and see each HTTP status code.
FAQ
What is a canonical tag?
A canonical tag (<link rel='canonical' href='...'>) tells search engines which URL is the preferred version of a page when multiple URLs serve the same or very similar content. It consolidates ranking signals to a single URL and prevents duplicate content penalties.
When should a canonical be self-referential?
Most pages should have a self-referential canonical — the canonical URL matches the page's own URL. This is a best practice signal that tells search engines there is no preferred alternative version. Only set a different canonical when you intentionally want to consolidate signals from a duplicate or near-duplicate page.
What happens if a canonical tag is missing?
Without a canonical, search engines may identify multiple versions of your page (HTTP/HTTPS, www/non-www, with/without trailing slash, URL parameters) as separate pages and split ranking signals across them. Always set an explicit canonical to avoid accidental duplicate content.
Can I use a canonical to consolidate signals across domains?
Yes, cross-domain canonicals are supported by Google. If you publish the same content on two different domains and prefer one, set the canonical on the secondary domain pointing to the primary domain URL. Google will consolidate ranking signals to the canonical URL.
What is the difference between a canonical and a 301 redirect?
A 301 redirect physically sends users and bots to a new URL — the old URL is no longer served. A canonical leaves the original URL accessible but signals which version is preferred for indexing. Use a 301 when the old URL should cease to exist; use canonical when multiple URLs serve content that should be indexed only under one URL.