Canonical URL Checker
Short answer
Verify canonical tags to prevent duplicate content issues.
What It Does
Fetches your page and inspects the `<link rel="canonical">` tag: whether it exists, how many are present, and whether the URL is absolute and served over HTTPS. Flags missing, duplicate, relative, or HTTP-only canonicals that make it harder for search engines to pick the right URL.
Why It Matters
A wrong canonical tag can point search engines to a different URL from the one you want in the results, or to a URL that no longer exists. Paginated and filtered pages without canonicals can end up competing with each other, and one mistake in a shared template affects every page built from it.
How It Works
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Enter your page URL and run the check
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We fetch the page HTML and extract the `<link rel="canonical">` tag
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Check whether it's present, singular, absolute, and served over HTTPS
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Flag missing, duplicate, relative, or HTTP-only canonicals
Sample input + output
url: https://rankproof.eu/tools?ref=hn
<link rel="canonical">: present → https://rankproof.eu/tools count: 1 OK format: absolute URL OK protocol: HTTPS OK Score: 100/100
Who Uses This
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Technical SEO
After a migration, check the canonical tag on key pages and confirm it uses the new URLs.
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Developer
Catch CMS-generated duplicate canonicals on WordPress paginated archives before launch.
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Agency Account Manager
Find a canonical tag that points a client's page to the wrong URL.
Frequently Asked Questions
What is a canonical URL?
A canonical tag tells search engines which URL is the main version when several URLs show the same or similar content. Google treats it as a strong hint when choosing which URL to show. Duplicate content is not penalized as such; Google just needs to know which version you prefer.
What's the difference between a canonical and a redirect?
A 301 redirect sends visitors and crawlers to the new URL. A canonical tag leaves visitors where they are and only tells search engines which URL you prefer. Google treats a redirect as the stronger signal.
Can a page canonical to a different domain?
Yes — cross-domain canonicals are valid for syndicated content. Google must crawl and trust the target domain. This checker validates the tag's format (absolute URL, HTTPS) but doesn't compare it against the domain you're checking.
What causes canonical tag mismatches?
Common causes: CMS plugins generating wrong URLs, HTTPS/HTTP mixing, www/non-www inconsistency, trailing slash differences, and paginated URLs lacking proper canonicals.
Does every page need a canonical tag?
It is recommended. A self-referencing canonical on each page states which URL you prefer, instead of leaving the choice to Google.