Canonical Checker.

Test one URL or crawl a site for missing, invalid, and self-referencing canonical tags.

Canonical URL Checker

Canonical tags explained

What a canonical tag is and why you should test it

A canonical tag is a link element in the head of a page, <link rel="canonical" href="https://example.com/page/">, that tells search engines which URL is the preferred version of that content. When the same page is reachable at several addresses, for example with and without a trailing slash, with tracking parameters, or over http and https, the canonical consolidates ranking signals onto one URL and keeps the duplicates out of the index.

Google treats the tag as a strong hint rather than a directive, so a wrong canonical is worse than none: it can quietly remove pages from search or send signals to the wrong URL. This canonical checker fetches the live HTML of each URL and reports what it finds, so you can catch template bugs, CMS misconfiguration and migration leftovers before they cost traffic.

How to read the results

  • Valid canonical

    The page has a rel="canonical" link, it is an absolute http(s) URL on the same domain as the site you scanned, and it either points to the page itself (self-referencing) or to another page on the same site. This is the state you want on most pages.

  • Invalid canonical

    A canonical tag exists but the URL is not usable: it is malformed, uses a non-http(s) scheme, or points to a different domain than the one you scanned. Cross-domain canonicals can be legitimate for syndicated content, but on your own site they usually mean a copied template or a wrong base URL.

  • Missing canonical

    No rel="canonical" link was found in the HTML. Google will choose a canonical on its own, which is often fine for unique pages, but on pages with parameters, pagination or multiple paths it can pick a version you did not intend.

  • Failed to process

    The page could not be fetched or parsed: a 4xx or 5xx status, a timeout or a block from a firewall or bot protection. It is listed with the reason "Failed to process". Check that the URL loads in a browser and that the server allows automated requests.

In site mode the tool crawls internal links from the start URL you enter, so the summary at the end shows how many pages have a valid, invalid or missing canonical across the section you scanned. Use the filter to list only the pages that need work and download the CSV to share with your developer.

Common canonical errors and how to fix them

These are the problems that show up most often when we run canonical checks on client sites. Most come from templates and CMS settings rather than from individual pages.

  • Canonical points to a redirecting or 404 URL

    Fix: Search engines follow the canonical, so it must return 200. Update the tag to the final destination URL, matching trailing slash and https exactly.

  • Relative or protocol-relative canonical

    Fix: Use a full absolute URL (https://www.example.com/page/). Relative paths are easy to misresolve, especially on pages served under several paths.

  • http canonical on an https site, or the wrong www variant

    Fix: Every canonical should use the one host and scheme you want indexed. Set the site URL or base URL in your CMS so the tag is generated from it, not hard-coded.

  • Every page canonicalizes to the homepage

    Fix: This is a template bug that tells Google your whole site is one page. Make sure the canonical is generated per page, not copied from a layout file.

  • Paginated or filtered pages canonicalize to page 1

    Fix: Each paginated page should normally be self-canonical. Pointing them all to page 1 hides the products or articles listed on later pages.

  • Two different canonical tags on one page

    Fix: Often caused by a theme and an SEO plugin both adding one. Google may ignore both. Remove one so each page declares a single canonical.

  • Canonical conflicts with hreflang, sitemap or redirects

    Fix: The canonical URL, the URL in your XML sitemap, the hreflang targets and the final redirect destination should all be the same URL.

  • Canonical injected by JavaScript only

    Fix: Put the canonical in the server-rendered HTML head. Tags added only by client-side scripts are processed late or not at all.

Found canonical problems you cannot fix yourself?

Canonical issues on CMS sites usually need a template or configuration change rather than page-by-page edits. We fix canonical, redirect, sitemap and hreflang problems as part of our technical SEO work, including Joomla SEO services for Joomla and VirtueMart sites and SEO services for other platforms.

Other free SEO tools

How it works

Four steps.

  1. 01

    Enter the URL of the website or webpage you want to check for canonical tags. You can input a single URL or use the bulk upload feature to scan multiple URLs at once.

  2. 02

    Click 'Start Scan' to begin the process. The tool will validate each URL and check for canonical tags, highlighting any missing or invalid tags.

  3. 03

    Review the results in real-time as the tool progresses. Use the filter options to view pages with valid, missing, or incorrect canonical tags.

  4. 04

    Download a detailed report of the results, including all the URLs, their canonical status, and any issues found. The report is available in CSV format for easy sharing and future reference.

Features

What the Canonical Checker Does.

Audit canonical tags on one page or across a site, then export CSV results.

  • Single and Bulk URL Checking

    Scan one URL or perform bulk scans across multiple pages. The tool adapts to your needs, making it ideal for small websites and large-scale site audits.

  • Smart URL Validation

    The tool auto-formats and validates your URLs to ensure accuracy, reducing errors and improving the efficiency of the scan.

  • Real-Time Progress Tracking

    Monitor scan progress with a real-time progress bar. This feature is especially useful when scanning large sites, giving you transparency at every step.

  • Pause and Resume Scans

    Pause and resume your scan at any time, providing you with more control over the scanning process, particularly useful for larger websites.

  • Comprehensive Filtering

    Filter results to focus on key areas like missing, valid, or invalid canonical tags. This helps you prioritize fixes for better SEO outcomes.

  • CSV Report Download

    Download a full CSV report that includes all scan data, making it easy to share findings with your team or retain for later audits.

  • Detailed Scan Summary

    At the end of each scan, the tool provides a comprehensive summary of your website's canonical implementation, highlighting errors and successes.

  • SEO-Friendly Reports

    Receive SEO-optimized reports that guide you in resolving canonical tag issues, improving your site's search engine visibility.

  • Responsive and Mobile-Friendly Design

    Use the tool across devices, whether you're on a desktop, tablet, or smartphone, ensuring flexibility and ease of use wherever you are.

  • Error Notifications and Feedback

    Receive clear error messages and actionable feedback when issues arise, making it easy to fix problems and rerun scans quickly.

FAQ

Questions.

Can't find an answer? Send us your question.

What is a canonical tag?

A canonical tag is a link element in the head of an HTML page, written as , that tells search engines which URL is the preferred version of that content. It is used when the same content is reachable at more than one address.

How do I check the canonical tag of a page?

Turn on "Check single URL only" in the canonical checker above, enter the page URL and start the scan. The tool fetches the live HTML, reads the rel="canonical" link and reports whether it is present, which URL it points to and whether that URL is valid for the site. You can also view the page source in your browser and search for rel="canonical".

What does a valid canonical URL look like?

A valid canonical is an absolute http(s) URL on the domain you want indexed, returns a 200 status, and matches the URL in your XML sitemap and the destination of any redirects. On most pages it should point to the page itself. This tool flags canonicals that are malformed, non-http(s) or on a different domain than the one scanned.

Why are canonical tags important for SEO?

Canonical tags consolidate ranking signals from duplicate or near-duplicate URLs onto one preferred URL and keep the duplicates out of the index. Without them, search engines choose a canonical on their own, which can split link equity or index a version with tracking parameters.

What happens if my page is missing a canonical tag?

Google will pick a canonical itself based on signals such as internal links, redirects and sitemaps. For unique pages that is often fine, but on pages with parameters, pagination, filters or multiple paths it can choose a version you did not intend. Adding a self-referencing canonical removes the ambiguity.

Should every page have a self-referencing canonical?

It is a safe default. A self-referencing canonical confirms the preferred URL, including the exact host, scheme and trailing slash, and protects the page from being treated as a duplicate of a parameterized copy. Only pages that are genuine duplicates should canonicalize to a different URL.

Can a canonical point to a different domain?

Yes. A cross-domain canonical is used when the same article is published on more than one site and you want the original to be credited. On your own site, a canonical pointing to another domain is usually a mistake, which is why this tool reports it as invalid when the domain differs from the one you scanned.

Can I check canonical tags for a whole website?

Yes. Leave "Check single URL only" switched off and enter the base URL of the site or section. The tool crawls internal links from that page, checks the canonical on each page it finds, shows a live summary of valid, invalid and missing canonicals, and lets you filter the results and download them as a CSV.

Is the canonical checker free?

Yes. The canonical tag checker is free to use for single pages and site crawls, with no sign-up. Scans run from our server, so pages behind a login or blocked by bot protection cannot be checked.

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