Canonical tag

What we check

On the home page we look for the canonical tag, an element such as <link rel="canonical" href="https://www.example.ch/"> in the head of the page. Then we check:

• whether it exists (if it is missing, there is a note),
• whether there are several canonical tags with different addresses (warning),
• whether it points to another page of the same website instead of the home page itself (warning).

If the canonical points to an entirely different domain, the check "Readable and findable by Google" reports this as a serious defect.

Why it matters

The same page can often be reached under several addresses:

• https://example.ch/ and https://www.example.ch/
• https://www.example.ch/ and https://www.example.ch/index.php
• with additions such as ?utm_source=newsletter from campaigns

For Google these are at first different pages with the same content. The canonical tag says: "The valid address is this one." This way Google bundles all signals, such as links from other websites, on one address instead of spreading them.

If the canonical of the home page points to a subpage, for example /home or /de/, Google may put that one into the index instead of the home page. Google ignores several contradictory canonical tags altogether, which are often set by theme and plugin at the same time.

How to fix it

Every page should have exactly one canonical tag with its own full address:

<link rel="canonical" href="https://www.example.ch/">

• Use the full address with https:// and the spelling (with or without www) under which the website really runs.
• Do not let the canonical point to another page unless the page really is a copy of it.

WordPress

WordPress sets the canonical tag itself, SEO plugins such as Yoast SEO or Rank Math take it over and improve it. If several tags are present, theme and plugin usually set one each. Deactivate the function in one of the two places.

Wix, Jimdo, Squarespace

The builders set the canonical tag automatically. After a change of domain, check that the new domain is set as the primary domain.

How to check it yourself

Open the page source (right-click › "View page source") and search for rel="canonical". The address behind it should be exactly that of the home page.

Frequently asked questions

Is a canonical tag mandatory?

No, Google also manages without it. It does prevent variants of the same page from counting as duplicate content, though. That is why we give only a note when it is missing.

Is the canonical tag enough instead of a redirect?

It is a recommendation to Google, not a rule. For visitors it changes nothing. For spellings such as with and without www, a permanent redirect (301) is the cleaner solution.