If you own an eCommerce business you’ll know how key SEO is to your online presence, and how important this is for making your site easy to find for potential customers using search engines.

Magento is one of the most search engine friendly e-commerce platforms out there, however it’s not perfect, particularly when dealing with canonical urls in multi-store environments and on product listing navigation pages. Experts like SEOmoz highlight the importance of using canonicals correctly, stating “canonicalization is essential to proper SEO” (Canonicalization and the Canonical Tag – Learn SEO entry on SEOmoz). We’ve developed the Custom Canonical URLs for SEO Extension that let’s you extract the maximum juice from your canonical links and addresses these issues directly.

But…What does canonicalization mean?

Sometimes you can have a simple product in different categories. Let’s give an example to make it simple… one of the products you sell is the Kindle4 e-reader. This product will be under three different categories: e-Readers, Brands>Kindle & New Products. The final product page will have the same content in any of the three categories meaning that the same content is indexed under three different URL’s and guess what… search engines don’t like duplicated content. It’s considered a bad practice and in some cases “the ranking of the site may suffer or the site might be removed entirely from the Google index, in which case it will no longer appear in search results” (Duplicate Content entry on Google Webmaster Tools).

The solution is to write a canonical tag in the head section of your page, so that search engines will know how to index your site correctly without penalising you, and present the correct page in search results. In plain English, problem solved!

But doesn’t Magento do this already?

Well, sort of. Magento makes a decent effort by providing out the box canonicals that work generically, but it’s not as clever when it comes to some of the finer points of canonical URLs.

For example, Magento decides the canonical URL for a product when the product is first published – and this may include a category path. If your product is going to reside in multiple categories, you may not wish it’s canonical to reference the first category that it’s assigned – but there’s no way to change this in Magento.

Another problem area is Magento’s paging mechanism, which appears on category pages where multiple pages of products can be viewed sequentially by paging through them – this also attracts the unwanted “duplicate content” penalty (since there are many permutations of these pages). Luckily Google provides specialist canonical tags named “next” and “prev”, and a “show_all” concept to deal with these types of pages, and which your site should embrace to stay on the right side of SEO best practice.

“Next” and “prev” Canonical tag

The duplicate content issue can also be exacerbated if you publish multiple Magento stores on your site, perhaps differing only by currency, or language localisation (e.g. UK vs US English) – in which case Google will happily detect duplicate content. You need a way to instruct Magento (or rather Google) that these particular cross-store pages are, at least for SEO purposes, the same.

An easy way to address these issues on your Magento pages is to download the Custom Canonical URLs for SEO Extension extension. As well as dealing with the layered navigation paging mechanism, it easily allows you to set canonical URLs precisely (for any category, product or CMS page) and determine how your pages are referenced and indexed by search engines with fine-grained control. That means you avoid penalties for duplicated content, all without the help of a developer. It’s easy to implement and and works straight away with other SEO modules and Magento caching. It also lets you import your product canonicals en-masse using Magento’s standard spreadsheet product importer (to save time).

Williams Commerce is a Magento Enterprise Partner and has also developed other Magento extensions such as VeriFone, Shutl, Khaos Control, MNP OderActive and feefo. Williams Commerce’s clients include CIPD, MyTights.com, Pedlars, Start-rite Shoes and blow LTD.