--- title: "Canonical Tag Checker — Free Canonical URL Test" description: "Free canonical tag checker. Verify the rel=canonical URL of any page, catch conflicts between HTML and HTTP headers, and fix self-reference errors. No signup." canonical: "https://lemwatch.com/tools/canonical-checker" source: "https://lemwatch.com" --- # canonical tag checker > Check the canonical URL of any page. Finds missing, conflicting, relative, and cross-domain canonical tags — the quiet reason good pages drop out of the index. ## What this tool checks - rel="canonical" declared in the HTML - Link: rel="canonical" sent as an HTTP header - Conflicts between the HTML and header canonical - Whether the canonical self-references the requested URL - Relative, cross-domain, and redirecting canonical targets ## Why it matters A canonical tag tells Google which URL to keep and which to fold away. Point it at the wrong page and you hand your rankings to a duplicate; point two signals at different URLs and Google ignores both and picks for you. ## How to fix what it finds - Make every indexable page canonical to itself, absolute and https - Declare the canonical in one place only — HTML or HTTP header, not both - Never canonicalise a paginated page to page one; use self-canonicals - Ensure the canonical target returns 200, not a redirect or 404 - Match the canonical exactly, including trailing slash and casing ## This tool also answers ### Should a canonical tag point to itself? Yes, on every page you want indexed. A self-referencing canonical removes ambiguity from tracking parameters, session IDs and protocol variants, and it is what Google expects to find by default. ### What happens if two pages have the same canonical? Google treats them as one URL and keeps only the canonical target. That is correct for genuine duplicates and destructive when applied by accident — the non-canonical page stops ranking entirely. ## Frequently asked questions ### Is a canonical tag a directive or a hint? A hint. Google weighs it alongside internal links, sitemaps and redirects. If those signals contradict your canonical, Google may choose a different URL and report it as "Duplicate, Google chose different canonical" in Search Console. ### Can a canonical point to another domain? Yes, and it is valid for syndicated content — the original publisher gets the ranking. Do it by accident on a staging or CDN domain and you remove your own site from the results. ### Do I still need canonicals if I use redirects? A 301 already consolidates the URL, so the redirect target only needs its own self-canonical. Use canonicals for duplicates you must keep reachable, such as filtered or parameterised versions. ### Should a canonical tag point to itself? Yes, on every page you want indexed. A self-referencing canonical removes ambiguity from tracking parameters, session IDs and protocol variants, and it is what Google expects to find by default. ### What happens if two pages have the same canonical? Google treats them as one URL and keeps only the canonical target. That is correct for genuine duplicates and destructive when applied by accident — the non-canonical page stops ranking entirely. ## Related - [All free tools](https://lemwatch.com/tools) - [noindex checker](https://lemwatch.com/tools/indexability-checker) - [hreflang checker](https://lemwatch.com/tools/hreflang-checker) - [Meta Tags](https://lemwatch.com/tools/meta-tag-analyzer) - [Sitemap Checker](https://lemwatch.com/tools/sitemap-checker) - [domain age checker](https://lemwatch.com/tools/domain-age-checker) - [Lemwatch pricing](https://lemwatch.com/pricing) - [All monitoring checks](https://lemwatch.com/features)