AVAILABLE FOR WEB, FLUTTER & QA PROJECTS
How to use this tool
1. Paste HTML Head or Enter URLs
Paste your raw `<head>` tag snippet, test a live URL, or enter both page URL and canonical URL to compare.
2. Automatic Tag Extraction
The parser isolates all `<link rel='canonical'>` tags and evaluates attribute syntax.
3. Review Status & Warnings
Check for multiple conflicting tags, relative paths, trailing slashes, and HTTP/HTTPS parity.
4. Copy Clean Canonical Code
Generate and copy a valid, RFC-compliant canonical tag ready for immediate injection into your codebase.
Formula or logic used
Canonical Specification & RFC 6596 Rules
Search engines treat `rel=canonical` as a strong hint to consolidate link equity and eliminate duplicate content. Malformed tags are disregarded, leaving indexation to algorithmic chance.
Rule 1: Exactly one canonical tag per page. Multiple canonical tags invalidate each other.Rule 2: URLs must be absolute (e.g. https://domain.com/path), never relative (/path).Rule 3: Protocol, subdomain, and domain must match intended indexable versions.Rule 4: Trailing slash consistency must match internal link architecture (/page vs /page/).Rule 5: Self-referential canonicals should be present on every indexable canonical page.
Examples
Example 1: Clean Self-Referential Canonical
Protects the page against query parameter duplication from UTM campaign tracking or session IDs.
Example 2: Invalid Relative Path Tag
Relative canonicals are frequently misparsed across different subdomains and proxy layers.
Common use cases
E-Commerce Faceted Navigation Auditing
Verify that filtered product pages (e.g. ?color=blue&size=large) point canonical authority to the base category.
HTTP to HTTPS Migration Validation
Ensure legacy HTTP canonicals were not mistakenly hardcoded during SSL certificate upgrades.
Cross-Domain Syndication Tracking
Consolidate SEO ranking power back to original articles republished on Medium, LinkedIn, or partner blogs.
Trailing Slash Loop Prevention
Catch discrepancies between trailing slash redirects and canonical destination URLs.
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Frequently asked questions
What happens if a page has two canonical tags?
If Googlebot discovers multiple `<link rel='canonical'>` tags with different destination URLs, it will ignore both tags completely and use its own machine learning algorithms to select a canonical, which may not be the one you prefer.
Can canonical tags point to a different domain?
Yes. Cross-domain canonical tags are fully supported and recommended when syndicating blog articles across multiple external websites to ensure the original publisher receives all search ranking credit.
Is a canonical tag a directive or a hint?
A canonical tag is a strong hint, not an absolute directive like `noindex` or `robots.txt disallow`. Google may ignore your canonical if the designated canonical page returns a 404, redirects, or has substantially different content.
Should every page have a self-referential canonical?
Yes. Google Webmaster Guidelines recommend that every unique, indexable page include a self-referential canonical tag pointing to itself. This prevents duplicate indexation caused by UTM parameters, tracking strings, or URL case variations.
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