Google's Privacy Sandbox Asked an Industry to Volunteer for Worse Outcomes. The Industry Declined.

Google spent six years engineering a replacement for third-party cookies. The Privacy Sandbox moved ad targeting onto the device through Topics API, Protected Audience, and Attribution Reporting. Technically functional. Also, by every independent measure, significantly less capable than what it replaced.

Criteo's testing showed publisher revenue dropping 60%. Index Exchange measured CPMs falling by a third. Latency doubled. And the whole time, third-party cookies kept working fine in Chrome's 70% of the browser market.

By October 2025, Google began retiring the major APIs. The only survivors, CHIPS and FedCM, solved problems without asking anyone to sacrifice performance. Everything that required the ad industry to trade revenue for privacy died waiting for volunteers who never showed up.