Privacy Sandbox

The Privacy Sandbox is Google's initiative for Chrome and Android to build technologies that support advertising without cross-site tracking; Google kept third-party cookies in Chrome and retired most of the initiative's advertising APIs in 2025.

For several years the Sandbox was presented as the replacement for third-party cookies in Chrome. Its advertising APIs included Topics for interest-based ads, Protected Audience for remarketing, and Attribution Reporting for measurement. Privacy features such as partitioned cookies sat alongside them.

The plan changed twice. On 22 April 2025 Google said Chrome would keep its current approach to third-party cookie choice and would not launch a new standalone cookie prompt (Google, 22 April 2025). On 17 October 2025 Google said it would retire ten technologies, citing low adoption and feedback from the industry. They were Attribution Reporting, IP Protection, On-Device Personalization, Private Aggregation (with Shared Storage), Protected Audience, Protected App Signals, Related Website Sets, SelectURL, SDK Runtime and Topics. Google kept CHIPS, FedCM and Private State Tokens (Google, 17 October 2025).

Removal follows Chrome's release process, one API at a time, so some retired APIs still answered in some Chrome versions during 2026.

Example: Google's feature status page, last updated 14 August 2026, lists nine Chrome features as "continue to support", including CHIPS, FedCM, Private State Tokens and the Storage Access API. It lists eight Chrome features as "deprecate and remove", including Topics, Protected Audience, Attribution Reporting and Shared Storage (Google, Privacy Sandbox feature status).

Related terms: Topics API, CHIPS, UID2, EUID, cookie sync.

Authoritative source: Google, "Update on Plans for Privacy Sandbox Technologies" (17 October 2025).

Read the full guide: Identity after the Privacy Sandbox.