Canonical Tags | Improve Indexation & Control Perception of Crawlers

Canonical tags are an essential tool for helping to manage how search engines perceive and index your content. In the context of search engine optimization (SEO), canonicalization helps prevent duplicate content issues, consolidates link equity, and it ensures that the correct pages are ranked in search engine results pages (SERPs). This article will explain what canonical tags are, why they matter in SEO, and how you can use them to improve your site's crawl efficiency and indexation.

What Is a Canonical URL?

A canonical URL is the preferred version of a web page that search engines should prioritize when multiple URLs contain similar or identical content. Canonical URLs serve as the authoritative page to which link signals (like backlinks and internal links) should be directed. Utilizing canonical tags to specify which URL is “canonical”  helps search engines understand which page to rank and show in the search results.

For example, a website could have multiple URLs for the same content:

• https://example.com/page
• https://example.com/page/
• https://www.example.com/page

In this case, a canonical URL should be declared to prevent search engines from treating these variations as different pages.

What Is a Canonical Tag?

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

A canonical tag is an HTML element used to tell search engines which URL is the canonical version of a page. When a canonical tag is properly implemented, it informs search engines that even if there are multiple URLs displaying similar content, only one should be indexed and ranked in search results.

Canonical tags are commonly used to:

• Resolve duplicate content issues
• Consolidate multiple URLs into one authoritative version
• Maintain control over which pages are shown in search results

Why Does Canonicalization Matter In SEO?

Canonicalization is vital for SEO because it helps prevent duplicate content issues. Search engines penalize or de-prioritize websites with duplicate content, as it can be seen as an attempt to manipulate rankings. By using canonical tags, you signal to search engines which content to prioritize, ensuring that only one version of the page is indexed.

Additionally, canonical tags help:

• Consolidate link equity: If multiple URLs exist for the same content, the link equity (i.e., the SEO value passed by external and internal links) can be diluted. Canonical tags consolidate link equity to the page you choose, boosting the authority of the chosen page..
• Improve crawl efficiency: Canonical tags help search engines focus their crawl efforts on the most important pages, conserving your site’s crawl budget.

When To Use Canonical Tags

It is typically best-practice to use canonical tags on each page of your site. But, many site owners don’t, and you don’t technically need to. However, here are certain situations where you absolutely need to use canonical tags:

• Duplicate or similar content: If your site has multiple URLs displaying similar or identical content (e.g., product pages with different parameters), use a canonical tag to point search engines to the main version.
• Paginated pages: Use canonical tags on paginated content to consolidate the content signals to the primary page.
• Cross-domain content: If your content is syndicated across multiple domains, canonical tags can indicate the original source to avoid being penalized for duplicate content.

How To Add Canonical Tags In Your Website

Adding canonical tags is a straightforward process that involves editing your page’s HTML header. The basic format looks like this:

1<link rel="canonical" href="https://www.example.com/preferred-page-url/">

Ensure that the canonical URL is the full, absolute URL, including the protocol (http/https) and the domain.

Adding Canonical Tags In Webflow

If you're using Webflow to manage your website, you can add canonical tags by going to the page settings and manually entering the canonical URL in the custom code section. This helps ensure your Webflow pages are indexed correctly by search engines.

Canonical Tags & SEO Best Practices

Here are some of the most common situations where canonical tags are an absolute necessity to help improve your rankings, prevent penalties, or recover from penalties:

Use Canonical Tags for Duplicate or Similar Content

Always use canonical tags when you have multiple URLs showing the same or very similar content. This ensures search engines only index the main version, avoiding penalties for duplicate content.

Self-Referencing Canonical Tags

Even if a page is the only version of that content, it’s a good idea to implement a self-referencing canonical tag. Self-referencing canonical tags tell search engines that this page is the authoritative version, preventing accidental duplicate content issues.

Avoid Conflicting Canonical Tags

Ensure that you’re not sending mixed signals by having conflicting canonical tags. For example, don't use one canonical tag on your page but reference a different page in your XML sitemap. Consistency is key to proper canonicalization. If a URL changes in your Sitemap, make sure that you update the canonical tag. In fact, if you ever update a URL, always make sure to update the canonical tags pointing to it.

Use Proper Canonicalization for Paginated Pages

For paginated content, it’s essential to link to the primary page while still allowing the individual paginated pages to be crawled for content signals. This helps maintain the authority of the main page while ensuring the other pages are still indexed. It also helps prevent duplicate content issues revolving around paginated pages. You’d also want to utilize rel=”next” and rel=”prev” tags to further indicate that each page in the series is just that - a paginated series of pages. Checkout our guide on pagination to understand how to implement technical SEO to optimize paginated content properly. Our guide will help you avoid common mistakes, indexation issues, duplicate content penalties, and more.

Canonical Tags in Syndicated Content

If your content is syndicated (republished) across other websites, use canonical tags on those external sites to point back to the original version of the content on your website. This ensures that your version of the content is indexed and prioritized. By utilizing canonical tags on the syndicated content you’ll ensure that your version on your website will gain any link equity earned..

Canonical Tags in HTTPS vs. HTTP

Google prefers secured versions of webpages, so always canonicalize the HTTPS version of your content. You can point canonical tags to HTTP versions, but you will likely not rank as highly as you would’ve just by making the HTTPS version canonical instead.

Use Consistent URL Formats

Be consistent in your URL formatting. Always use the same URL conventions across all URLs on your site. If you use one version of your URL, always use that same version. If you use trailing slashes, always use them.

Monitor Canonical Tags With Google Search Console

Use Google Search Console to monitor how Google interprets your canonical tags. The Coverage Report will show you which pages Google has indexed and how it’s handling your canonical URLs. The URL Inspection Tool in Search Console is also valuable for checking if Google is using the canonical URL you've specified. Just note that a canonical tag alone doesn’t ensure Google uses your chosen URL as the canonical URL. It helps, but Google doesn’t always agree.

Benefits To Using Canonical Tags

Canonical tags help you take control of which pages are considered the true intended page that you want to show up in search results. Along with this come many different benefits such as:

Prevent Duplicate Content

Consolidating duplicate pages under one canonical URL helps prevent search engines from indexing multiple versions of the same content.

Consolidate Link Equity

Canonical tags help to ensure that any links pointing to slightly different versions of the same page will pass all link equity to the version you choose to make canonical. For example, some links might be pointing to the version of your page with just www., others might point to the http://www version, and the primary one you should use as canonical would be the https://www version.

Improve Crawl Efficiency

Canonical tags help to focus crawl efforts by reducing duplicate content, showing prioritized versions of your pages, and by helping crawlers better understand your site structures. Proper usage of canonical tags can be a great way to make crawlers more efficient when inspecting your pages.

Prevent Indexation of Unwanted URLs

Canonical tags allow you to guide search engines to ignore URLs that are not meant to be indexed, such as dynamically generated pages or filters. Your canonical tags can be ignored if crawlers determine certain pages have good unique information on them, so be careful of how you are structuring your content, and of the types of content you have on pages you don’t want getting indexed.

Control Content Syndication

By implementing canonical tags on syndicated content, you can ensure your original page gets the link equity instead of the republished versions.

Enhance User Experience

Canonical tags help users find the most relevant and authoritative version of a page, ensuring that they’re always directed to the correct content.

Mistakes To Avoid When Adding Canonical Tags

Even though canonical tags are a powerful tool, improper use can lead to serious SEO issues. Here are some common mistakes to avoid:

Canonicalizing The Wrong URL

Always double-check that the canonical URL you’re pointing to is the correct one. Canonicalizing the wrong URL can lead to indexing issues and loss of SEO value.

Using Canonical Tags Across Different Domains

If you're managing multiple domains, ensure that canonical tags point to the correct domain. Cross-domain canonicalization is allowed, but it's crucial that you have ownership or permission for the canonical URL.

Improper Paginated Page Canonicalization

Ensure that when you’re adding canonical tags to a series of paginated pages that you use dynamic text so that each page can be complete with the URL and page number. You’d also want to use rel=”next” and rel=”prev” tags to ensure that each page effectively communicates that it is part of a paginated series.

jAn example of a canonical URL with pagination would look like:

<link rel=”canonical” href=”https://www.example.com?page=”12”>

Here’s an example of a rel=”next” and rel=”prev” tag being used:

<link rel=”prev” href=”https://www.example.com?page=”11”>
<link rel=”next” href=”https://www.example.com?page=”31”>

Forgetting To Update Canonical Tags When Updating URLs

When changing URLs, always remember to update the canonical tag accordingly. If you don’t, search engines may index the wrong version of the page.

Relying On Canonical Tags To "Fix" Duplicate Content Issues

While canonical tags can often prevent duplicate content issues, they shouldn’t be used as a crutch. Whenever possible, eliminate the need for duplicate content entirely, either by consolidating pages or using proper redirects.

Common Canonical Tag Errors

Canonical tags can sometimes be misused, leading to common errors, such as:

• Conflicting canonical signals (different canonical tags on the same page)
• Pointing canonical tags to redirected URLs
• Having multiple canonical URLs on a single page