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Nutter Tools

A free toolbox that runs in your browser. A tool for every job.

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Everyday

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For developers

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© Nutter Toolsnutter.tools
  1. Home
  2. Network
  3. Canonical tag checker
Your files stay on your device

Canonical tag checker

Fetches a page through the project proxy and validates its rel=canonical: presence, duplicate tags, absolute URL, self-reference versus cross-page target, and whether the target resolves.

This tool is in beta

Still being tested. If a result looks wrong, tell us.

Report a problem

Press the button to check the page

Nothing leaves this page until you do. The report grades five rows: presence, duplicates, absolute URL, self versus cross-page target, and whether the target resolves.

The scan reads the HTML the proxy returns, which is capped in size, so a canonical declared past that cap would be missed; the report says when the body was cut. Tags anywhere in the document count, not just the head. The scan is a tag scan, not a full HTML parse, and no JavaScript runs, so a canonical injected by client-side code stays invisible. A cross-page canonical is reported as a fact, not a fault: it is the right setup for print views, parameter variants, and paginated series.

Page URL

One absolute http(s) URL per run

What leaves your browser

The page and its canonical target are fetched through this project's capped proxy server (GET only, public hosts only, size and time caps, rate-limited), because a browser cannot read cross-origin HTML itself. The canonical target gets one extra fetch of the same kind. This page leaves your browser only when you press the button; never on load, never in the background. Nothing is sent anywhere else. Google Analytics still measures the visit to this page, and it never receives what you run through this tool.

More network tools

  • HTTP timing probe
All network tools

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