Canonical tag checker, online and free to use
The tag that decides which address gets indexed, and the six ways it breaks
A canonical fault is almost always systemic: a template writes the wrong tag and a whole section inherits it. This tool confirms one page, a crawl finds the pattern.
Everything is computed in your browser. Nothing is stored.
Most sites serve the same page at several addresses without ever meaning to: with and without a trailing slash, on www and on the bare domain, over http and https, with a tracking parameter appended by a campaign. A canonical tag is how you decide instead of letting Google guess. It rarely fails by being absent: it fails by being present and wrong, which is far harder to notice.
How to use it
How it works
Paste an address
The tool reads the page and pulls out its canonical tag, its robots directive and its og:url.
Read the six checks
Presence, absolute address, self-reference, protocol, conflict with a noindex, agreement with og:url.
Fix the template, not the page
A canonical fault almost always comes from a template: the same mistake repeats across a whole section.
Worth knowing
Four things to keep in mind
Everything pointing at the homepage is the worst case
It is the classic migration bug, and it takes a site out of the index in a fortnight. If only one check gets done after a rebuild, make it this one.
A canonical is a hint, not an order
Google weighs it against your internal links, your sitemap and your redirects. When those signals contradict it, the canonical is usually the one that loses.
Never combine noindex and canonical
One says do not index this, the other names the version worth indexing. Google generally follows the noindex, and the canonical stops doing anything at all.
A paginated page references itself
Pointing page three at page one hides the rest of the series. Every page in a paginated set carries its own canonical.
FAQ
Frequently asked questions
Every indexable page, yes, and on a normal page it points at itself. Without one, Google picks a canonical from the duplicates it can see, and its choice is not always yours.
A redirect removes the duplicate: the old address is no longer visitable. A canonical keeps both reachable and only consolidates the index. Redirect when the old URL should disappear, canonical when both must work.
The canonical decides which address is indexed, og:url which one shares are credited to. When they diverge, your shares pile up on one address and your ranking signals on another.
Google has to re-crawl the page and its duplicates: days on a frequently visited site, weeks on a small one. Search Console URL inspection shows the canonical it actually chose.
Also
Other tools in the same family
Also
What Lokvi does for you
Now imagine all of it running without you
Review collection, replies, posts and loyalty, on your Google Business listing, automatically.
No credit card required: create your account and explore your real data.
14 days free, then 29 €/month, no commitment.