Canonical Tag Checker
Check rel=canonical against the real URL
What Is the Canonical Tag Checker?
The Canonical Tag Checker reads a page's rel=canonical after rendering it, compares it part by part with the URL that actually answered, and checks the mistakes that quietly remove pages from Google: relative canonicals, tracking parameters, canonicals outside the head, tags that disagree with og:url or the Link header, and canonicals that point at a redirect or a noindex page.
Key Features
One Page, Many Addresses
Every site generates duplicate URLs on its own: campaign parameters, sort orders, trailing slashes, http and https. The canonical tells Google which address is the real one. When it's right you never notice it. When it points somewhere else, the page can drop out of search without a single error in your logs.
What It Compares
The canonical is judged against the URL that answered after redirects, the way a crawler sees it. Tracking parameters like utm_source don't count as a different page, but a real parameter like ?page=2 does, so a paginated page that canonicalizes to page one is reported as pointing elsewhere.
Common Use Cases
- Working out why a page disappeared from Google
- Checking templates after a site migration
- Making sure campaign URLs consolidate into the clean page
- Auditing syndicated or duplicated content
Frequently Asked Questions
Is the Canonical Tag Checker free?
Yes. It's free with a ProxyHorizon account, and every account gets 25 runs a day shared across all our data tools. You can read about the tool without signing in, but running it needs an account because each run fetches live data.
Is the canonical a rule Google must follow?
No, it's a strong hint. Google weighs it with redirects, internal links and sitemaps, and can ignore a canonical it doesn't believe. Getting the signals to agree is what makes it stick.
Should every page have a self-referencing canonical?
Every page you want ranked, yes. It costs nothing and protects the page from the parameter and slash variants a site creates by itself.
Why does it fetch the page twice?
Once rendered in a real browser and once as plain HTML. When JavaScript adds or changes the canonical, the two differ, and that's worth knowing because Google reads the HTML first.
Do you store my results?
No. We log which tool you ran, what you entered and when, so we can apply the daily limit. Results aren't saved, so export them as CSV or JSON if you want to keep them.
Auditing sites or tracking SEO every day?
Proxies for SEO monitoring