With Google’s CSS (Comparison Shopping Service) model, advertisers have the opportunity to implement their shopping campaigns in cooperation with a price comparison portal. Why CSS partnerships are worthwhile for online shops and what needs to be considered.

After Google was punished in 2017 for abusing its monopoly power in Google Shopping and introduced the CSS (Comparison Shopping Service) model, online shops advertising have the opportunity to implement their shopping campaigns in cooperation with a price comparison portal.

The end of the shopping monopoly

Since the EU’s record competition penalty, Google’s own Google Shopping Europe (GSE) service is no longer the only price comparison service that can be used to bid for advertising space on Google Shopping. Since then, GSE has had to take part in auctions with external providers – the so-called Comparison Shopping Services. Similar to the tax advertisements, the bidder with the highest bid secures the advertisement.

Since then, advertisers have had the choice of either implementing their Google Shopping campaigns themselves or entering into cooperation with CSS partners who submit bids on behalf of the retailer. Traditional price comparison providers are also given equal opportunities and the opportunity to be more visible in the product search engine.

Lower CPCs through Google Shopping CSS

While the conversion to the CSS model is hardly apparent to users, the advertising online shop receives considerable price savings: For shopping ads via Google Shopping Europe, Google charges a 20 percent margin on the click prices, which are not applicable for delivery via the CSS partner.

As a result, the auction is also reduced by the ad rank by 20 percent, which has a direct impact on the advertiser’s performance and can mean a decisive disadvantage compared to the competition. In order to generate attention for the new shopping model and avoid further penalties, Google dropped the corresponding commission for CSS partnerships – to the advantage of the advertiser.

What to look for in CSS partnerships

Most CSS providers pay a monthly fee for the cost of running their own price comparison service.

Small traders in particular with a low budget should therefore double-check whether the margin that is lost may be offset by the fixed costs of the CSS partnership. For large online shops, however, working with one or more partners is usually profitable.

In addition to the available budget, the strategy is also decisive: especially retailers who have placed their focus on performance and efficiency can benefit from CSS partnerships. Since the close cooperation with a CSS requires trust, advertisers should also attach importance to the quality and the support service of the provider.

How to choose a CSS partner?

If you can work with one or more providers, how do you go about choosing a CSS supplier? The key differences between Comparison Shopping Services include:

Service Models

A Managed Service will let you provide your product data directly to your CSS, and they handle optimising your feed, uploading it to Google, and managing your campaign. Self-Service means you manage your Merchant Centre and Google Ads accounts once they’ve been created by your CSS.

Experience and expertise

This doesn’t just apply to implementing bidding. In addition to the quality controls and requirements enforced by Google, pan-European campaigns require a knowledge of the laws and product restrictions in each country.
This comes largely from experience, working with thousands of retailers on a daily basis and providing solutions for every challenge they might encounter.

Additional Services

Data enhancement and optimisation can deliver a big increase in sales conversions. And the wealth of data from a Premium CSS Partner can feed into your other marketing efforts, along with providing answers to any queries or problems which may occur.

Billing Models

Many CSS providers will operate on a Cost-Per-Click (CPC) basis with an additional fee on your bids or a monthly retainer. For example, Google Shopping will add a 20% charge onto bids before they are entered into the advertising auction. But it’s possible for an optimised campaign to be run on a CPA basis, which means you only pay a commission when you make a sale.


Experience and huge amounts of data come with scale, allowing your CSS to benchmark your efforts and understand where the biggest improvements can be made. Look for partners who have worked with high volumes in the industries and regions which apply to your business. One key comparison will be the size and reach of each CSS website. Does it reach millions of visitors who will also be directed to purchase your products?

Ultimately you’re unlikely to lose anything in trying a new CSS partner. It’s fairly quick and easy to run trials and test performance in just a few weeks. From that you can find your optimal Digital Shopping Mix which offers the best combination of results.

It’s time to switch

Working with a CSS brings about 20% savings on the CPC for Google Shopping for every online shop. There are no disadvantages.

So if you want to fight for the best ad spaces with a full bid on Google Shopping, you can’t avoid using CSS.