Topics API

Google-developed browser API positioned as the primary cookieless interest-based targeting alternative within the Privacy Sandbox framework

The Topics API was a browser-based advertising technology developed by Google as part of its Privacy Sandbox initiative, designed to replace third-party cookies for interest-based advertising. Rather than tracking users across websites via cookies, the API inferred a small set of broad interest categories — such as 'Sports' or 'Travel' — directly on the user's device from their recent browsing history, then exposed those topics to participating advertisers and ad tech vendors without revealing the underlying browsing data. This approach aimed to preserve a degree of advertising relevance while significantly reducing cross-site tracking and fingerprinting risks. Launched for general availability in Chrome in 2023 following an extended origin trial period, the Topics API represented Google's attempt to balance advertiser demand for audience targeting with growing regulatory and consumer pressure around online privacy. The API was integrated into Chrome's browser engine and made available to ad tech platforms, publishers, and advertisers as a cookieless targeting signal. It attracted significant industry attention and testing from major DSPs, SSPs, and publishers, though adoption was uneven and skepticism remained from both privacy advocates — who argued it still enabled tracking — and advertisers who questioned its targeting precision compared to cookies. Google officially retired the Topics API on October 17, 2025, as part of a broader strategic reversal in which the company abandoned its plan to deprecate third-party cookies in Chrome. Instead of eliminating cookies, Google pivoted to a user-choice model that allowed individuals to set their own privacy preferences. With third-party cookies remaining available in Chrome, the core rationale for the Topics API dissolved, and Google wound down the API along with several other Privacy Sandbox advertising relevance proposals. Its legacy lies in sparking industry-wide debate about privacy-preserving advertising alternatives and influencing subsequent standards discussions.