Third Party Tracking in the Mobile Ecosystem

TL;DR

This empirical study analyzes third-party tracking across nearly one million apps from the US and UK, revealing widespread tracking, category differences, and international jurisdiction issues, highlighting significant legal challenges.

Contribution

It provides a large-scale empirical analysis of third-party tracking prevalence, distribution, and jurisdictional aspects in mobile apps, which was previously underexplored.

Findings

Most apps contain third-party trackers.

Tracking distribution is long-tailed with dominant trackers.

News and children's apps have higher tracker counts.

Abstract

Third party tracking allows companies to identify users and track their behaviour across multiple digital services. This paper presents an empirical study of the prevalence of third-party trackers on 959,000 apps from the US and UK Google Play stores. We find that most apps contain third party tracking, and the distribution of trackers is long-tailed with several highly dominant trackers accounting for a large portion of the coverage. The extent of tracking also differs between categories of apps; in particular, news apps and apps targeted at children appear to be amongst the worst in terms of the number of third party trackers associated with them. Third party tracking is also revealed to be a highly trans-national phenomenon, with many trackers operating in jurisdictions outside the EU. Based on these findings, we draw out some significant legal compliance challenges facing the tracking industry.