The Rise and Fall of Google's Privacy Sandbox
2026-07-01 • Cryptography and Security
Cryptography and Security
AI summaryⓘ
The authors studied Google's Privacy Sandbox, a project aimed at improving online privacy while still allowing some advertising and tracking. They tracked how much websites used the Privacy Sandbox tools over several years before Google decided to stop most of them in 2025. They found that very few sites actually used these tools, and usage was decreasing. The only tool still being supported, CHIPS, showed some activity but no overall growth. The authors conclude that the challenge of private yet effective advertising online remains unsolved.
Privacy SandboxAPIsonline advertisingtrackingCookies Having Independent Partitioned State (CHIPS)web privacydata collectioncross-site trackinglongitudinal studyGoogle
Authors
Rachid Youssef Grib, Alberto Verna, Nikhil Jha, Martino Trevisan, Marco Mellia
Abstract
On October 17th, 2025, Google announced the retirement of most Privacy Sandbox APIs, concluding nearly five years of experimentation with its alternative to privacy-invasive data collection on the Web. Designed to balance privacy with advertising functionality and cross-site tracking, the initiative faced repeated redesigns and limited ecosystem support. In this work, we present the first longitudinal, consent-aware measurement of the Privacy Sandbox's deployment across the Web. Using a custom call listener and weekly crawls of the top-10,000 websites, we monitor the usage of all major APIs in the months preceding their retirement. Adoption had already stagnated well before Google's announcement: most APIs were used by only a handful of actors, whose activity declined steadily throughout our study. Even the APIs that Google plans to maintain show no sign of growth. The sole exception is Cookies Having Independent Partitioned State (CHIPS). Overall, the demise of the Privacy Sandbox leaves unresolved the challenge of enabling privacy-preserving interest-based advertising.