Free canonical tag checker
A canonical tag checker that reads a page's rel=canonical and tells you what it actually does: whether it points at the page itself, points away to a different URL, or is relative when it should be absolute. The tag that quietly de-indexes pages, made visible in one lookup.
The tag that de-indexes pages without warning
A canonical tag is small and its effect is large. When it points at a different URL, it tells search engines to treat this page as a copy and index the other one instead — which is exactly right for a duplicate, and a quiet disaster on a unique page you are trying to rank. The trap is that the page looks completely normal to anyone visiting it; the only symptom is that it never appears in search, and the cause is one line in the head. Checking the tag directly is the fastest way to rule it in or out.
Self-referencing is the healthy default
For nearly every page, the right canonical points at itself. It states “this URL is the original” and removes the ambiguity that arises when the same content is reachable through tracking parameters, a trailing slash, or an uppercase character. A page with no canonical at all is not broken — search engines will usually pick the right URL on their own — but a self-referencing tag takes the guesswork away, which is why most content management systems add one automatically.
Make every signal agree
The canonical is a hint, not a command. Google weighs it against your internal links, your sitemap and any redirects, and if those disagree it can pick a canonical you did not declare. So the reliable approach is to make them consistent: link to the canonical URL from other pages, list that URL in your sitemap, and point the tag at it. When two pages genuinely share content, the duplicate content checker shows how much they overlap and whether they already declare the same canonical — the correct fix for near-duplicates.
Where this fits
The canonical is one of the signals that decide whether a page is indexed at all. The others — the robots meta tag, the X-Robots-Tag header, the HTTP status — sit alongside it, and the indexability checker reads them together for a single verdict. The meta tag checker covers the rest of the head. For everything in one pass and a score out of 100, run the free website checker, and read what counts as a good score to interpret the result.
Canonical tag questions
- What does a canonical tag checker do?
- A canonical tag checker fetches a page, reads its rel=canonical link, and resolves that URL against the page you fetched. It then tells you the one thing that matters: whether the tag points at the page itself (self-referencing, the healthy default) or at a different URL (which tells search engines to index that other page instead of this one). It also flags a relative or malformed canonical, a common and easily missed mistake.
- What is a canonical tag?
- A canonical tag is a link element in a page's head that names the authoritative version of that page's content. When the same or very similar content is reachable at more than one URL — with and without a trailing slash, with tracking parameters, printer-friendly versions — the canonical tells search engines which one to treat as the original and index. The others defer to it, consolidating ranking signals onto a single URL instead of splitting them.
- What is a self-referencing canonical?
- A self-referencing canonical is a tag that points at the page it sits on. It is the correct default for almost every page: it states plainly 'this URL is the original', which removes ambiguity when the same page is reachable through parameters or slight URL variations. If a page has no canonical at all, search engines will usually guess, and they mostly guess right — but a self-referencing tag removes the guess.
- What does it mean when a canonical points to another page?
- It means the page is telling search engines 'do not index me — index that other URL instead'. That is exactly what you want on a duplicate or a parameter variant, and exactly what you do not want on a unique page you are trying to rank. A canonical pointing at the wrong URL is a quiet way to de-index a page you care about, and because the page looks normal to a visitor, it often goes unnoticed for months. This tool flags a canonical that points away so you can confirm it is deliberate.
- Should a canonical URL be absolute or relative?
- Always absolute — including the protocol and domain, like https://example.com/page. Google can process a relative canonical, but it is fragile: it resolves against the current URL, so a small server misconfiguration can point it somewhere unexpected. An absolute canonical has no ambiguity. This tool flags a relative canonical as something to tighten up even when it happens to resolve correctly.
- Does a canonical tag guarantee which page Google indexes?
- No — it is a strong hint, not a directive. Google treats the canonical as one signal among several, alongside internal links, the URL in your sitemap, and redirects, and it can choose a different canonical than the one you declared if the other signals disagree. The way to get what you want is to make all those signals agree: link internally to the canonical URL, list it in your sitemap, and point the tag at it. When they conflict, Google decides.
- Why is my canonical tag pointing to the wrong page?
- A mispointed canonical usually comes from a template or plugin that hardcodes one URL across many pages, or from a CMS setting left on a default. Check the tag the tool reports against the page you are on — if they differ unintentionally, Google may drop your page in favour of the one you accidentally named.
- What happens if a page has two canonical tags?
- When a page declares more than one canonical URL, Google treats the conflicting signal as unreliable and may ignore both, falling back to its own choice. Every page should output exactly one canonical tag, so audit for a theme and a plugin both inserting one, which is the common cause.
- Should a canonical tag be on every page?
- Every indexable page benefits from a self-referencing canonical that points to its own preferred URL, because it removes ambiguity from parameters and tracking variants. It is not strictly required when there is no duplication, but including one consistently is the safer default.
- What is the difference between a canonical tag and a 301 redirect?
- A 301 redirect sends both users and crawlers to a different URL, retiring the original, while a canonical tag keeps both pages accessible and only tells search engines which one to index. Use a redirect when a page should no longer be reached, and a canonical when both must stay live but only one should rank.
- Can a canonical tag point to a different domain?
- Yes — a cross-domain canonical is valid and is the correct tool when the same content is published on more than one domain, such as syndicated articles. It tells search engines to credit the original domain, though Google treats it as a strong hint rather than a guarantee.