Validate

Canonical Tag Validator

Paste a page’s HTML source and, optionally, its URL. The validator finds canonical tags in the <head>, flags common mistakes, resolves relative URLs and tells you whether the canonical points to the page itself. Your HTML is treated as text and never run.

Back

1. HTML source

Treated as text

2. Report

Nothing fetched
Paste HTML and press Validate.

Only the pasted HTML is checked. No page, canonical URL or search engine is contacted.

About this tool

About Canonical Tag Validator

Canonical Tag Validator reads the HTML source you paste and checks its rel="canonical" tags. It reports a missing canonical, multiple or empty canonicals, relative, malformed or fragment URLs, unsupported protocols and tags placed in the body, and — when you enter the page URL — whether the canonical is self-referencing.

Conflicting or broken canonical tags can split ranking signals between duplicate URLs or point search engines at the wrong page. Checking the source catches these mistakes quickly.

How to use

Step by step

  1. Copy the page’s HTML source (for example with View Source) and paste it.
  2. Optionally enter the page URL to resolve relative URLs and check self-reference.
  3. Press Validate.
  4. Review errors, warnings, passed checks and notes.
  5. Copy or download the full report.
Key features

What it offers

  • Missing, multiple and empty canonical detection
  • Relative, protocol-relative and malformed URL checks
  • Unsupported protocols such as javascript: and ftp:
  • Fragment (#) URLs flagged
  • Canonicals pushed into the <body> detected, as browsers parse them
  • Self-referencing check with trailing-slash and http/https hints
Best practices

Tips for best results

  • Use exactly one absolute https:// canonical in the <head>.
  • Place the canonical before any element that could end the <head> early.
  • Point duplicates to the version you want to rank, and make that version self-referencing.
  • Keep canonicals consistent with redirects, sitemaps and internal links.
Benefits

Why people use it

Thorough

Covers the common canonical mistakes.

Accurate

Parses HTML the way browsers do.

Safe

Pasted HTML is never run.

Private

No URL is fetched.

FAQ

Common questions

It reports a missing canonical, exactly one valid canonical, multiple canonicals, an empty href, relative or protocol-relative URLs, malformed URLs, unsupported protocols such as javascript: or ftp:, URLs with a #fragment, and canonical tags placed in the <body>.
Browsers and search engines end the <head> at the first element that is not allowed there, such as a <div>, an <img> or stray text. Any canonical tag after that point is treated as part of the <body> and ignored. The validator parses your HTML the same way a browser does.
Relative canonicals work in principle but are easy to get wrong, for example on staging copies or when a <base> element is present. A full https:// URL removes the ambiguity.
A self-referencing canonical points to the page’s own URL. Enter the page URL to check this; the tool also points out when the two differ only by a trailing slash or by http versus https.
No. It only reads the HTML you paste. It cannot see HTTP Link headers, redirects or what the canonical URL returns.
No. It is a strong hint, not a command. Search engines may choose a different canonical if other signals — redirects, internal links, sitemaps — disagree.
Yes. It is parsed into an inert document: scripts do not run, images and other resources are not loaded, and nothing from it is inserted into this page.

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Canonical Tag Generator

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Generate SEO meta tags — title, description, keywords, robots, author, charset, viewport, and theme color — with a live search-result preview. Copy or download the HTML.

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Private by design

This runs entirely in your browser

No file or text you enter here is uploaded. Encoding and decoding happen on your device using native browser APIs — close the tab and nothing remains on a server.

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