Ecommerce sites rely on filtered or faceted navigation to make their product catalogs more easily digestible for customers. Depending on how filters and facets are implemented, however, they can either be fantastic for search engine optimization or a big failure.
SEO is based on three pillars: crawler access, keyword relevance, and authority. Filters and facets affect the first two of these pillars, access and relevance. Depending on which platform is used and how it’s implemented, faceted navigation and filters can act as crawl barriers for search engines or produce tremendous amounts of duplicate content. That’s the access issue. If a search engine’s crawler can’t or doesn’t access certain pages on the site, those pages have no chance of being indexed, ranking or driving organic search traffic.
On the relevance front, pages created by filters and facets are often treated as subsets of the unfiltered page. As a result they aren’t allowed to display unique title tags, headings meta descriptions and other textual signals that would alert search engines to their unique content. Filtered and faceted pages may contain subsets of products that have high search value, but if the page isn’t allowed to display keyword signals targeting unique keywords, the page looks to a search engine nearly identical to the unfiltered page and all of its other filtered variants.
Example: When Facets and Filters Work for SEO
For example, when searching Google for the phrase “computer accessories” — 3,600 searchers do that each month — Overstock.com ranks in the third position, Office Depot is spot number eight, and PC Connection rounds up the first page in tenth place. Each of these ranking pages is a category or subcategory page linked from the primary navigation. As such they’re easily accessible to search engine crawlers, have relevant anchor text, and optimized on-page elements like title tags and headings to declare their keyword relevance.
The picture changes radically when the search results are filtered or narrowed using the faceted navigation feature on each of these sites. If the Google search is narrowed to “Belkin computer accessories,” Overstock ranks number two behind Belkin’s own site. Office Depot and PC Connection fall out of the top 50 Google search results, though. What is Overstock doing so well that Office Depot and PC Connection lack?
The page on Overstock that ranks number two in Google for “Belkin computer accessories” has implemented faceted navigation optimally for SEO to enable crawler access and send keyword relevance signals. Office Depot and PC Connection have not.
The image above shows the source code for Overstock’s Belkin Computer Accessories page and the page that displays when you visit in your browser. Highlighted in red are the elements that Overstock’s faceted navigation feature inserts into the page to allow it to send unique keyword signals: title tag, meta description, H1 heading, breadcrumb, URL. If the platform hadn’t been implemented to insert these keyword signals, this page specific to Belkin brand computer accessories would look exactly like its unfiltered parent page, Computer Accessories. It would have the same title tag and other SEO elements listed above as hundreds of pages in the Computer Accessories product subcategory.
In addition, Overstock has ensured that it implemented faceted navigation that is crawlable. Remember that search engines don’t accept cookies, and don’t traditionally execute CSS or JavaScript commands. With those three technologies disabled, Overstock’s faceted navigation remains crawlable via plain HTML text links. This is critical to enabling search crawlers to index every valuable page in the site.
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