What is a CSS?

CSS stands for comparison shopping service, which enables retailers to place Shopping ads in the carousel. CSS websites collect product information and offers from online retailers to advertise on Google Shopping. In order to use Google Shopping, Merchants must work with at least one CSS.

As it happens, Google Shopping itself is a form of CSS since the carousel provides ads for the same product from different retailers. However, Google Shopping works in an auction-based system: retailers tell Google the maximum bid they’re willing to pay to appear first in the carousel.

In recent years, the European Commission sued Google for monopolising the platform as they were the only provider enabling merchants to sell via Google Shopping. Now, other CSS providers can operate on Google Shopping in the EU.

How does a CSS account affect your overall performance on Google Shopping?

Advertisers who operate with an external CSS partner effectively use two separate Merchant Center accounts for the same website. In turn, this enables retailers to appear twice in the same Shopping Ads results. However, the same SKU cannot be advertised multiple times in the same search.

What’s more, as part of Google’s effort to avoid monopolising the platform in Europe, retailers using a CSS partner benefit from a 20% discount on their CPC fees. This means that on top of increased impression share (and increased opportunity for website traffic), clicks made through this external partner cost the retailer 1/5th less.

Retailers using Google Shopping with a CSS partner can subsequently reduce average CPC, boost their ROAS, and increase profitability.

In summary, partnering with an additional CSS provider is only available in Europe. Using a CSS enables retailers to appear twice in the same Shopping results carousel.

On top of that, user clicks through a CSS Shopping ad cost retailers 20% less. This opportunity to appear twice on the carousel and reduce your CPCs helps drive your performance on Google Shopping.

Introducing Bidnamic's CSS

Bidnamic recently introduced our very own CSS offering. Now, existing and even brand new clients can benefit from a CSS with Bidnamic, managed using our machine learning, human thinking approach.

Our data analysts and customer success managers provide personalised structure calls to ensure your account(s) are set up correctly and running smoothly.


For more Google Shopping news, FAQs and 'How-Tos', check out our resources. We've created a guide to conversion rate optimisation (CRO) featuring six advanced technologies from leading global MarTech companies - discover their unfair advantages here.

Interested in adding a CSS to your approach and conquering Google Shopping? Book a call with one of our Google Shopping Specialists today.

Jak Mortimer

Jak Mortimer

Jak is a Senior Data Analyst at Bidnamic. He works alongside clients to optimise their Google Ads accounts. He also plays a major role in the transition phase, ensuring a smooth experience and continued success.