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Canonical

Wygard watches the href of the <link rel="canonical"> tag on every monitored URL and alerts you the moment it changes.

Scope Tier Default Alert
Per URL Basic Enabled on every URL where a canonical is found 🔴 Danger

Why it matters

The canonical tag tells search engines which URL is the authoritative version of a page. A silently changed canonical — whether from a CMS update, a new plugin, or a botched deploy — can redirect indexing signals to the wrong URL and collapse organic traffic overnight.

Because the damage is hard to notice from the site itself (the page still loads, still looks fine), this test defaults to Danger: alerts fire immediately after the crawl batch finishes, not on the daily recap.

What Wygard checks

On every run, the crawler:

  1. Fetches the monitored URL.
  2. Extracts the href attribute of <link rel="canonical"> from the page source (or the rendered DOM, if JS rendering is enabled for that test).
  3. Compares the found value against the stored desired value.

The first run's value becomes the baseline. Every later run is compared to that baseline until you change the desired value or confirm a new one.

Common alerts

  • Canonical href changed — the tag now points to a different URL than the baseline.
  • Canonical not found — the <link rel="canonical"> tag was removed from the page.
  • Multiple canonicals — more than one canonical tag was detected. Search engines will pick one, often unpredictably.

Why the default is Danger

A canonical pointing to the wrong URL can deindex a page without any visible symptom on the site. The Danger severity is there so you see the alert inside an hour, not at the next daily digest.

Responding to an alert

  1. Open the alert from your email or dashboard and review the diff — Wygard shows both the previous and the new canonical.
  2. Decide whether the change was intended (e.g. you consolidated two URLs) or accidental (e.g. a template regression).
  3. If it was intended, use Set found value as desired on the alert card to adopt the new canonical as the baseline.
  4. If it was accidental, fix the template or configuration on your site. The next crawl will turn the test green automatically.

Pair it with Self-canonical

The standard Canonical test watches the URL as-is. If your site serves parametrized URLs (e.g. from UTM campaigns, filters, or search), also enable the Self-canonical test — it catches CMSes that rebuild the canonical to include query parameters.