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Discoverability

How to set canonical URLs correctly

A canonical tag pointing at the wrong target tells search engines to index that page instead of this one — every page pointing at the homepage removes your whole site from search except one URL, while everything still looks correct in a browser. With no canonical at all, the same page reached through a tracking parameter, a trailing slash or the www host can be treated as several competing pages.

What 13x checks

This is rule discoverability.canonical in the public registry: Canonical URLs are set and consistent. It runs on every audit, against the pages we actually fetched, and its result is derived from the response rather than estimated.

Surface
Discoverability
Score weight
8 of the readiness score
Scope
Reported as skipped when the page renders only with JavaScript
Applies
To every site

Registry version 2026-07-30. Every rule is published, and the audit is deterministic — the same page produces the same finding every time.

The fix

The same text the audit hands you when this check fails on your own site.

Give every page a self-referencing canonical URL — absolute, and matching the URL you want indexed:

html code
<link rel="canonical" href="https://example.com/this-exact-page" />

The failure this check reports is usually a canonical hardcoded to the homepage in a shared layout, which tells search engines every page is a duplicate of /.

Framework-specific versions

Where the change differs enough to be worth writing out separately.

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