Canonical Tag Checker

How It Works

Enter a page URL and paste the HTML head section (or fetch from URL). The tool detects canonical tags, og:url, and robots meta directives. It verifies whether the canonical tag is self-referencing (pointing to itself), points to the correct URL, and flags potential duplicate content issues. The 3-column status overview shows canonical presence, self-referencing status, and og:url alignment.

Why It Matters for SEO

Canonical tags tell Google which version of a page to index when multiple URLs serve similar content. Without proper canonicalization, Google may split ranking signals across duplicate pages, diluting your SEO authority. This is critical for e-commerce sites with faceted navigation, sites with www/non-www or HTTP/HTTPS variants, and pages accessible via multiple URL formats. Google estimates that 30% of the web has duplicate content issues that canonical tags can solve.

When to Use This Tool

• Before publishing to ensure canonical tags are correctly set
• When diagnosing duplicate content issues in Google Search Console
• After URL restructuring to verify canonical redirects
• During site migrations to preserve canonical signals
• For e-commerce sites with faceted navigation and filtered URLs
• When syndicating content to other sites with proper attribution

Key Concepts

Best Practices

• Always include a self-referencing canonical tag on every page
• Use absolute URLs in canonical tags (not relative paths)
• Ensure the canonical URL returns a 200 status code (not a redirect or 404)
• Set canonical to the preferred version when multiple URLs serve the same content
• Don't canonical to pages that are noindexed or blocked by robots.txt
• Keep canonical tags consistent — don't point different pages to different canonicals

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Frequently Asked Questions