Canonical Tag Best Practices for eCommerce Websites
The canonical tag has been accepted by all major search engines as a trusted solution to resolve the issue of duplicate content on a website since February 2009. Canonical tags are simple to apply. You can think of them as 301 redirects without the actual redirect. They are a real boon for ecommerce websites with layered navigation for ease of use and better conversation optimization.
If used effectively canonical tags can put your visitors on the right pages for optimum sales and your ecommerce website might not be victim of duplicate content search penalties. This post should provide you with better idea about how to use canonical tags for e-commerce websites.
Canonical Tag for Home Page
Problem: A website’s homepage generally has more than one URL, depending on the hosting service provider. All of these URLs take users to the homepage. Here are some examples:
Search engines consider different URLs to be different pages and hence this becomes a major problem for content duplicity.
Solution: Duplicate content can be resolved by implementing the canonical tag in all of the example pages above, and pointing them to one defined URL. Google doesn’t differentiate between a URL with a forward slash (/) or without it. However, the best practice is to have URLs end with a forward slash because this tells the search engines that the URL has ended and speeds up the page loading process.
Category Pages with Pagination
Problem: If you have products listed on more than one page under any specific category, duplicate content becomes an issue again. And hence, creating a relationship between these pages that search engine spiders can understand becomes very problematic. Another big issue can be of the duplicity between the root page and page 1 URL when there are several pages of items listed in a category:
Solution: Google recommends the “View All” page to be specified as the canonical tag recipient. For Google this is similar to merging all the pages together in one single document (View All) and giving it to Google. Implementing the same canonical tag onto each of the pages of a category is all what you need to do to accomplish this. The canonicalisation to the “View All” page would look something like this:
<link ref=”canonical” href=”http://www.example.com/category-1?page=all” />
However if you have too many products in a single category, this may not be such a good idea. It will increase page load time and search engine spiders prefer not to spend too much time indexing a single page.
On the other hand, if you don’t have a “View All” option with the pages, the only solution is to implement the rel=”next” and rel=“prev” HTML elements. For example, the first page would include the following element in the <head> section of the site:
<link rel=”next” href=”http://www.example.com/category-1?page=1” />
In the same way, the second page would include:
<link rel=”prev” href=”http://www.example.com/category-1” />
<link rel=”next” href=”http://www.example.com/category-1?page=2” />
And this would continue through all the pages.
Product Tags Pages
Problem: Tags are one of the main causes of content duplicity. They may create different URLs that have the same content. See below for some examples:
Solution: It is always best to use canonical tags pointing to the root product or category page on all the duplicate pages in order to solve the problem of content duplicity. As long as Google has a clear path to products, indexing every variant may causes more harm than good.
One Product, Multiple Categories
Problem: Generally one product, in an e-commerce website, is listed in more than one category. Something like this:
This creates the issue of duplicate content on pages with different URLs.
Solution: One thing you can do is setup the product page URL like this:
Using this method you can list as many products as you want in any categories without putting the category name in the URL. However, if you want to keep the category in the URL, you need to select a URL and point canonical tags from other pages to it. You can then add canonical tags from the category URL to the product-only URL.
But if you can’t do that, there is another solution that is a bit more laborious. You need to analyze your site’s data and traffic to find out the most dominant URL. In this way you an choose the best URL to point the canonical tags. Then you can simply implement the canonical tag onto each of the pages.
Problem: In most e-commerce sites, layered navigation is used with categories to make it more user-friendly. There can be many filters for layered navigation like: Size, Price, Discount, Color, Manufacturer etc. Here are some examples showing how URLs change when these filters are applied:
Layered navigation can cause duplicate content for this reason.
Solution: To solve the layered navigation duplicate content issue, Google advises adding canonical tags from all of these pages to the root URL. i.e. to:
Another thing that can be done is to use hash tags. Append the URL elements of filters after a hash tag. Google is not able to read anything after a hash tag and hence these pages won’t get indexed. Here is an example:
However, conanicalisation to the root URL is more preferably used as hash tags may not be reliable in the future.
Problem: The main problem with product pages is that there are different URLs for the same product with different sizes, colors, designs and reviews. As the product code changes, the URL changes something like this:
This is again the case of duplicate content.
Solution: adding canonical tags pointing to the most popular version of the product can solve this. To do this, you have to determine which page is the default version of the product that has the most traffic.
URLs with Search Parameters
Problem: The problem of duplicate content arises again when users search something by typing his/her query in the search box of the website. Different URLs are created with every different query. Here are some examples:
Sometimes search engines index these URLs because the search engine spider does not have any clear instructions for crawling them.
Solution: The choice really depends on you and how you want to have your site indexed. Generally it is best to add canonical tags for all search result pages to a default search page unless you have any special features on search.
Information (CMS) Pages:
Problem: Most of the information pages like about us, shipping, privacy etc. do not have duplication problems, however sometime duplication of these pages can occur with SSL versions (HTTPS.)
Solution: to overcome this problem it’s a good idea to use canonical tags on all these informative pages in your CMS. The tags will guide search engine spiders and show them which pages they should index.
It is always an important and needful practice to use canonical tags onto your website in order to remove duplicate content. Please make sure you implemented it properly.
External Resources: SEO advice: url canonicalization By Matt Cutts , Head of Webspam, Google.
All right! Hope you’ve enjoyed this Post. Please Don’t hesitate to share your thoughts and ask your questions in the comments; I’ll do my best to answer.