GoogleSiteScore
Free tool

Canonical URL Checker

Check any URL's canonical tag. Detect missing, mismatched, or cross-domain canonicals that quietly kill your rankings.

Pro tips

Always self-reference

Unless the page is truly a duplicate, canonical should equal the page's own URL.

Full URLs only

https://www.example.com/page — protocol + host + path. No relative paths.

One canonical per page

Multiple canonical tags = Google ignores all of them.

Learn: Canonical URL Checker

Everything worth knowing, in plain English

What a canonical tag actually does

A canonical tag is a single line of HTML that lives in the <head> of a page: <link rel="canonical" href="https://example.com/product-a"/>. It's Google's official way to say "this URL is the definitive version of this content." When Google finds the same or nearly-identical content on multiple URLs, it uses canonical tags to decide which one to index and rank.

Without canonicals, you'll accidentally split ranking signals across duplicate versions of a page (www vs. non-www, http vs. https, trailing slash vs. not, tracking parameters, category paths). This shows up as pages that "should be ranking" mysteriously not ranking, or as "Duplicate without user-selected canonical" warnings in Google Search Console.

The five most common canonical mistakes

1. Every page canonicalizing to the homepage. This tells Google every page IS the homepage — and it will drop the others from the index. 2. Canonicals pointing to the http version when you moved to https. Google may keep indexing the old insecure URLs and losing traffic. 3. Relative URLs in canonicals ("/product-a" instead of "https://example.com/product-a"). Google usually handles these correctly, but any parsing glitch means the tag is ignored. 4. Canonicals that don't actually exist (pointing to a 404). Silently ignored. 5. Multiple canonical tags on the same page. Google will pick one at random.

Use the checker above to spot these. If your canonical is missing, wrong, or self-referencing to the wrong URL, fix it once and Google usually picks up the change within 1–2 weeks.

Cross-domain canonicals — the advanced use case

You can canonicalize from your domain to someone else's. This is how syndicated articles work — if you republish a post from another blog, you add a canonical tag on your version pointing to the original. Google then credits the original with all ranking signals and treats your copy as a legitimate republish, not duplicate content. This is the right way to handle guest posts, press releases, and Medium/LinkedIn cross-posts.

Frequently asked questions

A <link rel="canonical"> in the <head> that tells Google which URL is the authoritative version of a page.

Related SEO tools

Redirect Checker →Meta Tag Tool →Google Index Checker →

Or browse all SEO tools in the toolkit.

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