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Canonical URL Checker

Analyze HTML source to extract and validate canonical tags, or quickly compare page and canonical URLs to prevent duplicate content issues.

HTML Source

If provided, the canonical URL will be compared against this page URL.
Analysis updates as you type.

Check Canonical Tag

Validation updates as you type.

How It Works

This tool offers two ways to check canonical tags. The Analyze HTML tab parses your HTML source code to find <link rel="canonical"> tags, then runs a comprehensive set of validation checks against SEO best practices. The Validate URLs tab lets you quickly compare a page URL against its canonical URL to spot mismatches.

What Gets Checked
  • Tag presence — Verifies a canonical tag exists in the <head>
  • Duplicate tags — Detects multiple conflicting canonical declarations
  • Absolute URL — Ensures the href is a fully-qualified URL, not relative
  • Protocol — Checks for HTTPS usage and protocol consistency
  • Trailing slashes — Flags inconsistent trailing slash usage
  • Query parameters — Warns about URL parameters in canonical URLs
  • Self-referencing — Verifies canonical URL matches the page URL
  • og:url consistency — Compares Open Graph URL with canonical
Why Canonical Tags Matter
  • Duplicate content — Tells search engines which URL is the preferred version
  • Link equity — Consolidates ranking signals to a single URL
  • Crawl budget — Helps search engines avoid crawling duplicate pages
  • Cross-domain — Can point to content on a different domain for syndication
Best Practices:
  • Every page should have exactly one self-referencing canonical tag
  • Always use absolute URLs with HTTPS
  • Place the canonical tag in the <head> section, not <body>
  • Avoid canonical tags pointing to redirecting or non-200 URLs
  • Keep canonical URLs clean — remove unnecessary query parameters and fragments
  • Don't chain canonicals

Embed This Util

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML: 


    

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