Definition
Comparison Shopping Services (CSS) emerged from the European Commission's 2017 antitrust decision against Google, which forced Google to open its Shopping space to third-party comparison services. Certified CSS can serve Google Shopping ads on behalf of merchants, often with a 20% CPC reduction compared to direct Google Shopping (because Google does not take a margin on third-party CSS bids). Concretely, a merchant can go through a CSS partner rather than native Google Shopping for their Performance Max or classic Shopping campaigns. CSS operate in the European Economic Area (EEA) and Switzerland. The indirect SEO impact is significant: CSS increase visibility in Shopping results, generate qualified traffic, and strengthen brand signals. Major CSS in France include Kelkoo, Idealo, LeGuide.com, and Twenga.
Key Points
- Approximately 20% CPC reduction on Google Shopping via a CSS partner
- Born from the 2017 European antitrust decision against Google
- Available only in the European Economic Area and Switzerland
Practical Examples
Migrating to a CSS partner
A French e-commerce merchant migrates their Google Shopping campaigns to a CSS partner and achieves a 20% CPC savings. With the same budget, they get 25% more clicks on their product pages.
Multi-CSS strategy
A large retailer simultaneously uses Google Shopping CSS and two CSS partners (Kelkoo and Idealo) to maximize Shopping result coverage and test each comparison service's performance.
Frequently Asked Questions
It depends on the CSS model. Some take a percentage of the CPC, others charge a monthly subscription. Even with these fees, the 20% Google CPC savings often makes using a CSS profitable.
No, CSS are only available in the European Economic Area and Switzerland. For Shopping campaigns outside the EEA, only native Google Shopping CSS is available.
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Last updated: 2026-02-07