Missing canonical tag

Severity: Opportunity
Impact: Low
Effort to fix: Low
Issue code: canonical_missing

Why it matters

Without a canonical tag, search engines pick the preferred version of duplicate or parameter URLs on their own.

How to fix it

Add a self-referencing <link rel="canonical" href="..."> in the head.

What a self-referencing canonical looks like

<link rel="canonical" href="https://www.example.com/blue-running-shoes/">

Use the absolute URL of the page itself, with the same protocol, host and trailing slash your site uses everywhere else.

Why add one to every page

The same page is often reachable at several addresses: with and without tracking parameters such as ?utm_source=, with filter or sort parameters, with and without a trailing slash, or in upper and lower case. A self-referencing canonical tells search engines which version to index and consolidates links to it.

Most CMS platforms and SEO plugins add canonicals automatically. If yours does not, add it to the shared page template rather than page by page.

How it affects your score

Finding this issue on any page costs the Technical SEO score 0.5 points, plus up to 4 more depending on the share of crawled pages affected. A smaller improvement with a modest effect on its own.

Find the affected URLs

Open Crawl > Issues and pick Missing canonical tag. Each affected URL is listed with its evidence, and Copy URLs or Export URLs hands the list to a developer. The issue also appears in the Action Plan, ranked by impact (low) and effort (low), and in the issues CSV under the code canonical_missing. After fixing, run a new audit and use Compare to confirm the URLs moved to fixed.