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Canonical URL Data

Canonical URL

Canonical URL
Simple Definition
Values Returned
Canonical URLs in More Detail:
- A Bit More on URLs
Examples of How Canonical URL Data is Used
- Example 1: Is a Page Canonical?
- Example 2: Duplicate Pages
- Example 3: Missing Canonical Tags
Related Content
Benefits of Our Data


Canonical URL

If a page has a canonical tag, it will likely have a canonical URL. This determines what the preferred version of the page is and is aimed at stipulating that to Google. Used for a multitude of reasons, they are pretty much mandatory components of a webpage (from an SEO perspective).

Ensuring that every page has a canonical tag is best practice and optimising this can improve the overall SEO of a site. This is ever truer on large sites and has special implications with multi-regional and multilingual sites.


Simple Definition

This is the URL contained within the canonical tag on a page.


Values Returned

There is only one type of value returned in this column… and that is a URL, this is the first column in any export and is the address of the resource.

The possible values returned in this column are as follows:

URL = Canonical tag in the correct place in the code & contains a URL, we show the URL

Missing Canonical Tag = The canonical tag is missing

Error = The canonical tag is incorrectly implemented

BLANK = The canonical tag is in the wrong part of the source code.


Canonical URLs in More Detail:

The page must meet the following criteria to be determined or defined as a canonical page or canonical URL:

  • HTML/Text
  • Accessible
  • Return a ‘200’ status code
  • Linked to at least once
  • Contain a canonical URL that exactly matches the URL of the page

The only way we find URLs on your site is by following links on your site, site as navigation, footer links, sitemaps, XML sitemaps etc. That said there are some instances where we will guess a URL if we cannot find one, we expect to find.

This includes things like:

  • Index files
  • PDF documents,
  • Sitemaps
  • Robots.txt

This data is taken from the first canonical tag we find located in the correct location, should there be multiple tags implemented on a page.

This data is scraped from this canonical tag, using the example canonical tag below:

<link rel="canonical" href=" "/>

We would show this as the canonical URL:

If there is no canonical tag or it has no URL in it, the value will be left blank. Typically indicating that there is no canonical tag, or at least no useful one present.


A Bit More on URLs

The URL of a page is the only data / value returned so we thought it worth explaining in a little more detail. below is an example of a URL:

  • Internet Application Protocol (Protocol)
  • Sub-Domain
  • Top Level Domain (TLD)
  • Directory (Dir)
  • Sub-Directory (Sub)
  • Page or file / Resource

If you site does not use redirects to force things like HTTP, or if you link inconsistently, we will often find pages with different sub domains, protocols, trailing slashes, etc.


Examples of How Canonical URL Data is Used

All the data our web scraper extracts is used in various ways by SEOs or web devs. We provide some examples of how Canonical URL data can be used in different ways below:


Example 1: Is a Page Canonical?

This basic check is most useful on sites where canonical tags are implemented properly for the most part. You can determine which pages are canonical based on whether the Canonical URL matches the URL of the page. If they match, the page is canonical, but we also provide this check to you in another column titled “Page is Canonical”.

Often these pages are the primary focus of an SEO assessment or audit.


Example 2: Duplicate Pages

You can use this data to identify pages that are legitimate canonical duplicates of other pages. These pages can often be excluded from any analysis as they are non-canonical and hence do not require optimising in the same way as canonical pages.

Example 3: Missing Canonical Tags

A standard SEO check you can do with this data; is ensuring that every page that has a canonical tag, and that it is implemented correctly on page.


Related Content

The list of guides below might be useful if you are analysing this data and want to know more about it:

Related column headers in Raptor website crawler reports:


Benefits of Our Data

We are in currently in an early release phase and are continually adding new data, checks and analysis to our tools, we aim to add more components over the coming weeks and months.
Typically, the URLs are the result of your analysis, such as:

  • Pages missing a canonical tag
  • Pages with incorrect canonical tags
  • Canonical pages
  • Non-Canonical pages
  • Help with technical SEO audits
  • Improve SEO


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