What Is URL Normalization? Explain How It Works and How It Affects SEO

What is URL normalization

If you don’t normalize the URL, your site’s evaluation will be dispersed and Google will not evaluate it correctly.

However, I think that there are many people who do not know how to normalize the URL.

Therefore, in this article, we will explain in detail how to normalize URLs and the scenes where normalization is necessary. Please help us to manage the site.

What is URL normalization?

URL canonicalization is to determine a single canonical URL when multiple URLs exist for the same content .

For example, “https://○○.com/” and “https://www.○○.com/” are the same site, but as you can see, there are two URLs. In other words, the site with the same content exists at two URLs. This state is called “duplicate content”, and if the URL is not normalized in the state of duplicate content, the backlinks will be dispersed, which is not preferable from the SEO point of view.

By normalizing the URL, you can determine one canonical URL from the multiple URLs above. Since the content itself does not change even if it is normalized, there is no hindrance to the operation of the site. Since the evaluation of backlinks will be concentrated only on the normalized URL, it is rather possible to increase the search ranking.

In the end, there is no particular disadvantage to normalizing URLs, so be sure to do it when you operate your site.

Two ways to normalize URLs

There are two main ways to normalize URLs:

  • 301 redirect
  • canonical tag

Use “301 redirect” to eliminate duplicate content and use only one URL, and “canonical tag” to normalize URLs with parameters or URLs for PC and smartphone.

Let’s take a look at each method and see which one is right for you.

1.301 redirect

The most commonly used method is a 301 redirect . By eliminating duplicate content and having only one URL, you can collect backlink ratings to one URL. If you access the obsolete URL, you will be redirected to the regular URL.

In a simple example, when there are two duplicate contents “https://○○.com/” and “https://www.○○.com/”, “https://○○ .com/” is the regular URL, even if you access “https://www.○○.com/”, it will be connected to “https://○○.com/”.

The 301 redirect method differs depending on the web server environment, and it also changes depending on the content of the URL to be normalized. In some cases, the 301 redirect itself may not be possible in the first place, so if it is difficult, use the canonical tag.

2.canonical tag

Unlike 301 redirects, canonical tags do not abolish the URL, but can be instructed to summarize the evaluation from Google into the canonical URL .

If there is a difference in the URL between the PC site and the smartphone site, if the URL is abolished with 301 redirect, there is a risk that the smartphone will access the PC site. . In such a case, let’s summarize only the evaluation with the canonical tag. Also, as mentioned above, canonical tags are used even when 301 redirects cannot be used.

All you have to do is write the following in the head tag of the page you don’t want to collect ratings for.

<link rel=”canonical” href=” https://○○.com/”>

The point is to describe the URL of the person who wants to collect evaluations in the head tag of the page of the person who does not want to collect evaluations. Be careful not to turn it upside down.

Read Also: What Is an Anchor Link?

How to check URL canonicalization using Google Search Console

You can use Google Search Console to check if your URLs are normalized.

The confirmation method is as follows.

  • Open Google Search Console
  • Click “URL inspection” from the left menu
  • Enter URL
  • open coverage
  • Check user-specified canonical URLs and Google-selected canonical URLs

There is no problem if the canonical URL specified by the user is specified correctly and the canonical URL selected by Google is displayed as “URL to be inspected”.

By the way, you can also check whether the URL has been normalized by using the info command or a dedicated tool. If Google Search Console doesn’t work for you, try other methods.

5 cases where URL canonicalization is required

There are five main cases where URL normalization is required, including the presence or absence of “www” mentioned above.

Let’s check each case to see if it is necessary to normalize the URL for your site. Who should be normalized by URL is roughly decided. Be careful not to mistake the normalization method, as it can also affect Google search results.

1.Presence or absence of www

As mentioned above, if there are two URLs depending on the presence or absence of “www”, let’s normalize it. From the point of view of convenience, there is no problem even if both exist, but since the evaluation of the backlink will be dispersed, normalization will make it easier to improve search results. Remember that normalization is necessary for the same reason in the remaining four cases introduced next.

  • https://○○.com/
  • https://www.○○.com/

It doesn’t matter which URL you canonicalize.

The advantage of having www is that it is easier to understand that it is a URL. On the other hand, it also has the advantage that it is easier to remember the URL without the www. This is a matter of taste, so choose whichever is most convenient for you.

2.Presence or absence of index.html, etc.

The content will also be duplicated depending on the presence or absence of “index.html” at the end of the URL.

  • https://○○.com/
  • https://○○.com/index.html/

When there are two URLs in the above format.

Unlike “www”, “index.html” should not exist .

Since the URL will be long, it will not give a good impression visually. There is no particular advantage in adding index.html, so unless you are very particular about it, normalize the one without index.html.

Strictly speaking, the presence or absence of “/ (slash)” at the end of the URL is also related, so let’s remember.

3. Presence or absence of encryption (http:// and https://)

Content is duplicated with or without encryption.

Encryption is the difference between “https://○○.com/” and “http://○○.com/”, that is, whether or not there is an “s”. This “s” means Secure (safety), and as the name suggests, the site with “s” is more secure . Even Google’s official statement states that “https://○○.com/” is more secure for the site and will affect search rankings.

From the point of view of SEO, “http://○○.com/” without “s” is only a disadvantage, so “https://○○.com/” with “s” is always a disadvantage. Let’s normalize

4. Parameters

Parameters are variables attached to the end of the URL . There are some sites that assign parameters to each link to check the flow within the site.

Amazon is a good example, where parameters are given when accessing various product pages from within the site. If you search for a product on Google and the same Amazon product page is displayed in the search results just by changing the parameter part of the URL, it will be a problem.

So even if parameters are given, normalization is still required. Naturally, the URL to be normalized is the one without parameters.

5. Smartphone pages that do not support responsive design

Smartphone pages that do not support responsive design also need to be normalized.

Responsive design refers to a mechanism in which even if the same URL is opened on a PC, the page for PC is displayed, and when opened on a smartphone, the page for smartphone is displayed. If responsive design is not supported, there are many cases where URLs are created for both PC and smartphone. A common example is “https://○○.com/” for PC URL and “https://○○.com/sp/” for smartphone URL.

Even if the display format is different for PC and smartphone, if the content is the same, it will be considered duplicate content. So in this case we also normalize. It is common to normalize with URL for PC.

3 Reasons You Need URL Canonicalization

There are three main reasons why URL canonicalization is necessary:

  • Google not evaluating duplicate content
  • Distributed link ratings
  • Possibility of lower rankings and penalties

Some of the contents introduced so far are also included, but let’s understand the reason correctly and normalize the URL.

1. Google Is Not Evaluating Duplicate Content

Google doesn’t like duplicate content . Even on an internal site, if multiple URLs have the same content, there is a possibility that you will receive a bad evaluation.

By the way, it’s just an internal duplication, so it doesn’t affect the external site. Therefore, it is not clear whether duplicate content on the internal site will lower the rating. However, duplicate content itself is not viewed well, so normalization is a safe bet.

2. Distributed link evaluation

As mentioned earlier, link ratings will be scattered if URLs are not canonicalized. Therefore, even if you get a backlink, there is a high possibility that it will be lower than the original search ranking because there are multiple links.

Collecting backlinks for SEO is a very difficult task. Canonical tags can be put into practice right now. In order not to waste the precious backlink, let’s normalize quickly and unify the evaluation.

3. Possibility of lower rankings and penalties

In some cases, there is also the possibility of lower rankings and penalties. Since all URL normalization is completed on the internal site, the possibility of being penalized is extremely low, but as long as Google recommends normalization, I do not know what kind of response will be taken in the future. Therefore, it cannot be ruled out that there will be penalties in the future.

Also, in the unlikely event that Google determines that an unencrypted URL (http) is legitimate, it may cause a decrease in ranking due to security issues. In preparation for unusual cases, let’s normalize so that the encrypted URL (https) can be conveyed as a legitimate URL.

Effectively improve SEO with URL normalization

URL normalization improves SEO. As I’ve mentioned many times in this article, let’s review how URL canonicalization affects SEO.

The number of backlinks is important for improving the effectiveness of SEO . The more links you get from external sites, the more popular Google thinks your site is. And popular sites tend to appear at the top of search results as sites with high credibility. Roughly speaking, this means that the number of backlinks = popularity = good search ranking .

The problem is whether or not the URL is normalized. If the URL is not canonicalized, there will be multiple URLs and each will be evaluated. And since only one duplicate content is displayed in the search results, the links acquired on one side will be useless for SEO and the evaluation will be scattered.

For example, if there are two URLs “https://○○.com/” and “https://www.○○.com/”, “https://○○.com/” will receive 5,000 If you collect 5,000 backlinks even with the link “https://www.○○.com/”, it can be said that the site is popular enough to collect 10,000 backlinks. However, if URL normalization is not performed, one URL will be considered duplicate content and will not be displayed in search results, so only 5,000 backlinks will be reflected in search results.

For the above reasons, URL canonicalization has a big impact on SEO, so be sure to do it once you start operating your site.


URL normalization is a very important task for site management.

It takes a lot of work, but just normalizing it works positively for SEO, so there’s no reason not to do it. However, if you make a mistake with the URL to be normalized, it will take more time to correct it, so be careful not to make any mistakes.