Free Consultation
Home > Blog > SEO Blog > What is Canonicalization and How Does it Work?
Featured imagea Jul 28, 2022

What is Canonicalization and How Does it Work?

When business owners develop or upgrade websites as part of their digital marketing efforts, they may unknowingly create duplicate content. While this process will not cause penalties for a webpage, it may negatively impact search engine optimization (SEO) rankings.

Understanding how search engines view duplicate content and index URLs can help prevent unnecessary issues — for instance, you wouldn’t want another brand to rank for an article you wrote.

Google processes over 8.5 billion searches daily. If you want to dominate this online space, it’s time to understand what canonicalization is and how it works.

What Is Canonicalization in SEO?

Bots view websites differently than humans do. For search engines, every URL is a unique page. If consumers can access your homepage through different sources with similar content, Google will interpret them as duplicate versions of the same webpage.

Also called standardization or normalization, canonicalization in SEO is the process that search engines use to identify a site’s main — or “canonical” — version. Search results show one URL as the original and most valuable among duplicates and index it. Unfortunately, they sometimes choose the wrong one.

For this reason, it’s essential to take proactive measures to help these platforms identify which one is which.

What Is a Canonical Link?

As your site grows, it’s hard to avoid creating near-duplicate content that impacts your SEO efforts. This process of developing two or more pages using the same keywords might confuse Google and other search engines.

Check out an example of similar links below:

To address this problem, you can choose a preferred URL called the “canonical link”. Google defines this as the URL of the best representative from a group of similar pages.

If you oversee several pages that are nearly identical, Google can cluster them and choose one as the canonical link.

For example, if you create several pages for one product with various sizes, Google can cluster them. Remember, a duplicate can use a different domain name than the canonical link.

What Is Canonicalization Used For?

Once you determine your master link, you can use a canonical tag to tell search engines which URL represents it. With enough signals, they will redirect potential customers from search results to your preferred page.

Below are some cases in which we would recommend using a canonical tag:

  • Bots can reach your homepage through multiple URLs, like,, or
  • Your URL uses an HTTP version without SSL encryption.
  • You use duplicate content on various pages on your site, including those presented in different versions, such as PDF and XML.
  • You run a site like an eCommerce store with similar products with slight differences.
  • Your content is available on external websites.

You can use different techniques to add canonical tags, depending on your host and what your team deems best. Google recommends the following tactics, though each comes with its own distinct pros and cons:

  • If you have duplicate pages, add a link tag to the code.
  • Create a rel=canonical header in your page response.
  • Identify your canonical page in a sitemap.
  • Use 301 redirects to guide bots to a better version of a URL.
  • For accelerated mobile pages (AMPs), follow AMP guidelines to identify the canonical page.

Canonicalization Signals

Various signals go into the canonicalization process, including duplicates, sitemap URLs, canonical link elements, internal and external links, redirects, and hreflang. Google weighs these signals to identify the canonical link.

We’ll walk through each of them in more detail below.



Weighing Canonicalization Signals - SEO Infntech Designs


When faced with duplicate content, Google chooses the canonical version to index. The search engine will weigh different signals to perform this process, and the canonical link may change over time.

There’s no penalty for having duplicate content, but you want to index the correct page to enhance your digital marketing strategies.

Duplicate Signals Consolidate - SEO Infntech Designs

Below are some factors that may cause canonicalization issues:

  • Websites with HTTP and HTTPS counterparts
  • URLs with non-www and www variants
  • Links with and without trailing slashes
  • URLs that follow different capitalization
  • Pages with various versions, such as mobile, print, or international editions

Pro tip: Google usually prefers HTTPS pages over HTTP pages and shorter URLs over longer URLs. While these instances won’t gain you penalties, they may cause problems for your online efforts, like in these scenarios:

  • Google will choose a canonical, whether it’s your page or not. Even if your site is the original source of a piece of content, the search engine giant can choose a different URL to index.
  • Hreflang — the tool that specifies the language and geographic restrictions of a file — does not address duplication for international sites. Imagine how many potential buyers you might lose if your non-English content ranks for your English-speaking audience.
  • When you choose app shell models to build your site, the code may look similar to that of other pages. At times, Google’s algorithm can mistakenly group such pages in clusters.

Duplicate Detection - SEO Infintech Designs


Sitemap URLs

The URLs in your sitemap are also canonicalization signals. In most cases, you should only include the links you want to index.

However, there are exceptions to this rule, because these components help with crawling. For instance, after a website migration, you might want to keep old pages to ensure unbroken redirects.

Canonical Link Elements

A canonical element — commonly referred to as a canonical tag — is another canonicalization signal. You can create one to indicate your preferred site.

Google acknowledges this feature but ignores it if the other components are more powerful.

The canonical tag looks like this:

<link rel =”canonical” />

You can implement this tool in two ways: in the section or in the HTTP header.

Internal Links

Another way to help Google identify valuable pages is to use internal links correctly. These tools enable the search engine giant to understand your content and which of your pages are most important to you.

Generally, we recommend linking your pages to the version you want to index. However, in some cases, what’s best for users may trump other factors in the canonicalization process.


Backlinks are one of the most surprising canonicalization signals. As with SEO practices, it matters how external sources link to your pages. For this reason, it’s best to ask other sites to update their links to the latest version of your page.


The World Wide Web uses URL redirection or forwarding to make more than one URL address available for a page. It involves redirecting one URL to another. There are five common redirect types, and they’re all canonicalization signals.

Redirect Canonicalization Infintech Designs


  • 301: Page owners use this redirect type for websites that have permanently moved to another IP address.
  • 302: You can use 302 for URLs you want to temporarily move to another location. For instance, you can use it while your site is under maintenance or while you want to lead visitors to another link you’re promoting.
  • 303: Brands use 303 redirects when receiving POST data from a client, like after submitting a form.
  • 307: This redirect type indicates that the requested page temporarily moved to the URL provided in the Location headers.
  • 308: When you see this redirect type, it means your target resource moved to a new permanent uniform resource identifier (URI).


Hreflang is a tool that brands use to show which of the different pages of an international site should appear in a search. We recommend using canonicalization to indicate the best page to index within a country or language version.

How to Check the Canonical Link

We recommend three techniques to identify your canonical link; we’ll delve into the details of each one below.

  • The best tool to check which page Google chose as the canonical for your site is the Google Search Console. The site will ask you for a property type — a domain or a URL prefix. Afterward, key in the URL to reveal your declared canonical and what the search engine has chosen.
  • Another way to check the canonical is simply typing a URL into Google. In most cases, the top result is the canonical link.
  • Lastly, you can check a page’s cached version in the search engine. If it shows a different page, it means Google has selected a different page than the one you tagged.

Common Canonical Mistakes

Canonicalization is a complicated process, and many things can go wrong with it. Below are some of the most common errors page owners make in canonicalization.

Using the Wrong URLs

Other HTML tags accept absolute and relative URLs, and so should your tags. When you apply canonical URLs, make sure to define absolute URLs correctly.

Remember to include the http:// portion of the address in the website to avoid an indexing error. Failing to do so will cause Google to ignore your canonical tag.

Blocking the Canonicalized URL

Blocking any URL in robotx.txt prevents search engines from crawling it. The same concept applies to canonical tags on such pages.

When this happens, you don’t transfer any link equity from similar pages to the canonical one.

Having Multiple Canonical Tags

One of the most common canonicalization errors that page owners make is having multiple canonical tags for one page. Remember, they can come from various sources, like a theme, extension, or content management system (CMS).

Whatever the reason, this scenario confuses crawlers, making them ignore your tags altogether.

Setting the Canonicalized URL to “Noindex”

Keep in mind that rel=canonical and noindex tags are contradictory. In most cases, Google will prioritize the former, so you should never mix them.

Canonicalizing All Pages in a Series

Page owners use rel=canonical tags to define a site’s main version. However, you shouldn’t add canonical tags from all pages in a series. Otherwise, you risk crawlers ignoring them.

Applying Inconsistent Canonicalization Strategies

As discussed earlier, there are various canonicalization signals. Applying consistent strategies will clarify which canonical you prefer for Google.

However, if your efforts suggest different canonicals, the search engine will have trouble selecting the right page to index.

Ignoring Hreflang Tools

Like unicode, hreflang tags are essential because they identify the language and geographical area you want to target. When you use hreflang, remember to specify a canonical URL in the same language or the nearest possible substitute.

Final Thoughts

Canonicalization is essential for a brand’s digital marketing efforts. Getting it wrong may not incur penalties, but it can negatively impact your business strategies.

However, the process is complicated and requires a steep learning curve. If you want to dominate search engines, you need an experienced specialist on your side.

We discussed seven signals earlier today, but there are plenty of others. Just like SEO ranking factors, all of these components matter for your canonicalization efforts.

If you want to ensure the success of all your pages, a reliable digital marketing company can do wonders for your business. At Infintech Designs, we offer various services, including canonicalization, SEO, design, conversion, and web development.

Call 504-547-6565 now to request a free consultation. It’s the first ideal step to boosting your online presence.

More from Infintech Designs

What’s the Difference Between SEO and SEM?
How to Find the Best SEO Services for Your Small Business

Review Widget