Today, websites operate in a modular fashion, outsourcing the surveillance and datafication of users to outside companies, along with security functions, video hosting, and so on. These third-party services (TPSs) function as key enablers of the web, with respect to functionality and the monetization of user activity. Departing from critical data studies and media systems analysis, the article contributes to understanding TPS infrastructures by placing these in a wider context of markets, cultural differences and regulation. Through a study of top-150 websites from the 28 EU countries, the article demonstrates how the use of TPSs varies between different parts of the region and different types of sites, and traces this variation to issues of language, regulatory traditions and differences in online businesses. These insights may inform current debates about surveillance capitalism and big data, by linking different forms of commodification of users’ behavioural data to broader social and cultural structures.