Does every indexable page have exactly one clear canonical URL?
A single canonical tag per page tells AI crawlers which URL is the real one when several versions exist.
What this signal tests
We check that every indexable page on your site declares one - and only one - canonical URL, using either an HTML link tag in the page head or an HTTP Link header. The declared URL must use the secure https:// scheme, point to a real page that loads successfully, and not contradict any other canonical signal on the same page.
Why it matters for your visibility in AI
When the same content is reachable at several URLs - with and without a trailing slash, with tracking parameters, on a mobile subdomain, or under different categories - AI crawlers see what looks like duplicate pages. The canonical tag tells them which URL is the master copy, so all credit and citation signals consolidate onto one address. Without a canonical tag, those signals split across every duplicate, and none of the variants is strong enough to be cited. With conflicting canonicals - for example, an HTML tag saying one thing and an HTTP header saying another - the crawler picks one at random or ignores both, and your page may be dropped from AI answers entirely while a thinner competitor with cleaner markup gets cited instead.
Pass criteria at a glance
| Criterion | Passes when |
|---|---|
| 100% of sampled indexable pages pass. |
How we test it
For each indexable page in our sample we look in two places for the canonical declaration: the link tag with rel=canonical in the page head, and the Link header returned by the server. We confirm that exactly one value is present, that it is an absolute URL starting with https://, that following it leads to a successful 200 response with no redirect chain, and that the HTML and header values do not contradict each other.
Show technical detection method
Parse <link rel="canonical"> and Link header; assert exactly one resolved value per page, absolute HTTPS, 200, no redirect chain.
If your site fails: how to fix it
- Audit your templates and identify which one renders the canonical link tag in the page head. If none does, add it - most CMSs have a setting or plugin for canonical URLs.
- Make sure the canonical URL is rendered as a full absolute URL beginning with https:// and your domain, not as a relative path like /about.
- Remove any conflicting Link header that your server or CDN might be adding. The HTML tag and the HTTP header should never disagree - pick one and stick to it.
- For pages with query parameters used for tracking (utm_, gclid, fbclid, etc.), make sure the canonical points to the clean URL without those parameters.
- For paginated archives or filtered listings, point each page's canonical to itself (not the first page) so that each unique combination is indexable.
- Re-run the AI Ready Test and confirm 100% of sampled pages now have a single, valid canonical.
Quick facts
| Maturity | ESTABLISHED |
|---|---|
| Weight | high |
| Category | Crawlability |
Primary sources
Related signals
Frequently asked questions
Should my canonical URL point to the page itself or to a different page?
Usually to itself - this is called a self-referential canonical and is the safest default for any unique page. Only point to a different URL when you genuinely want crawlers to credit a different page (for example a syndicated copy crediting the original).
What about pages with tracking parameters in the URL?
The canonical should point to the clean version of the URL without any tracking parameters. This stops every campaign variant from being treated as a separate page and consolidates all the signals onto the single canonical URL.
Do canonical tags work the same way for AI crawlers as for Google?
Yes - the major AI search crawlers respect canonical signals the same way classic search engines do. A clean canonical setup helps both audiences simultaneously, and there is no AI-specific extra tag required for this purpose.
What if my homepage is reachable at both example.com and www.example.com?
Pick one as the canonical version and 301 redirect the other to it. Also set the canonical tag on every page to use the chosen hostname. Mixed canonicals across hostnames cause the same signal-splitting problem as duplicate paths.
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