February 3, 2023

How to Audit Canonical Tags for SEO

A canonical tag tells search engines which page they should prioritise when crawling a website where there are duplicate, or very similar, web pages. They are located within your HTML and are extremely useful for Search Engine Optimisation (SEO) to fix cannibalisation issues, remedy duplicate pages, help your site’s overall ranking performance and more. 

So, when you’re met with a website that has multiple canonical tags, how do you audit canonical tags for SEO? When looking at your canonical tags, there are 3 important factors that you need to consider. These are; recording each page that has a canonical tag, ensuring that the tag is placed correctly and directs crawlers to the correct landing page, and checking for any technical issues that are preventing the page from being crawled. 

Naturally, we all want our websites to perform to the best of their ability. A website producing duplicate URLs for the same page is a common occurrence that will need to be addressed to ensure that your rankings aren’t penalised. To help guide you through your canonical tag audits, we’ve written this short guide. Simply keep reading to learn more.

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How Do You Audit a Canonical Tag?

If you have canonical tags implemented on your website, it’s important that you regularly audit them to ensure that they are running correctly. Improper use of the canonical tag, or failing canonical tags, can significantly damage your rankings and overall website performance. For example, if your canonical tag directs crawl bots to a URL that has since been redirected, your tag will fail. Changes in your ever-growing website are normal, and a canonical audit is a simple way to ensure that everything is running as smoothly as possible.

The first step in conducting your canonical audit is to find the most practical way to check the status of your existing tags. If you have a short list of existing tags, then you may choose to do this manually. For larger websites, using a software tool to run a site-wide audit is the best and most time-efficient method to ensure everything is running as it should. 

Checking Your Tags Manually

To check your tags manually, you simply need to inspect the page. To do this, right click on the page and select ‘View page source’. From here you can use the search feature by pressing ‘Ctrl + F’ to search for ‘canonical’. Your tags (if present) will be highlighted for you to easily locate.

Once your tag is identified, you need to ensure that the tag uses the correct URL (preferably the original page source) and is located in the correct aspect of your HTML, which should be in the <head>. If everything looks good in your HTML, you then need to check the actual page and the content within it. This includes ensuring that your links aren’t broken, and running the URL through Google Search Console to ensure that there are no technical issues that are preventing the page from being crawled. 

Using Software to Conduct a Site Audit 

Alternatively, if you have a large website, or want to explore if any other URLs on your website are facing duplication problems, then using software to inspect your site may be the best way to audit your tags. Here, you can run your website through software such as Screaming Frog, Moz or SiteBulb to identify any issues. Typically, these types of software will be able to detect and report if a page requires a tag added to fix any technical issues, or if an existing tag is broken. This is a preferred method of audit to ensure that no pages on your website are missed. 

What are the Different Types of Canonical Issues?

When you are conducting your site audits, there are a variety of different canonical tag labels that you need to be aware of. We’ve listed all the essential information below:


This identifies that the page has a canonical set.


This page has a canonical tag set and the URL specified within the tag is the same page that has been crawled.


A ‘missing’ label means that this page requires a canonical tag to be set.


If a page is flagged as ‘canonicalised’, then a tag is present that is instructing crawl bots to index a different page that is not the current URL.


Non-indexed canonical warnings imply that the page the tag is directed to is a non-indexable page. This is a technical issue that will need to be resolved.


This is a warning that indicates that multiple pages are tagged to be directed to in the canonical. This will need to be amended to just one targeted URL.

Why Do I Need to Audit Canonical Tags?

If you do not audit your canonical tags, then you run the risk of technical failures penalising your ranking ability. This could be through pages being unable to index correctly, crawl bots being unable to correctly navigate your website, or duplicate content causing cannibalisation issues on essential landing pages. This is an essential technical skill that those within SEO should learn more about to fix what are extremely common issues. 

Get Help with Your Canonical Tags From the Experts at Wildcat Digital 

If you’re having trouble with your canonical tags, let the expert team at Wildcat Digital help. We are an experienced team of SEO experts that are ready to help any website achieve its best potential. Simply explore our website to learn more, or get in touch with us today to receive your free consultation. 

Post by

Rachel Moore

SEO Account Manager

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