Topics API

Topics was designed as a privacy-friendlier replacement for cookie-based behavioral targeting. Instead of letting ad tech companies track every site you visit, Chrome itself would look at your recent browsing, assign a handful of broad topics from a public list (such as "Fitness" or "Travel"), and share up to three with participating sites so ads could be relevant.

Topics were computed per week, kept on the device, drawn from a limited taxonomy of a few hundred categories that excluded sensitive ones, and included some random noise. Users could view and remove topics or turn the feature off. An Android version existed for apps.

Adoption and performance were mixed: many buyers found topics too coarse compared with cookies or first-party data, and some regulators and browser makers questioned its privacy properties. With Google keeping third-party cookies in Chrome, the case for Topics weakened, and in October 2025 Google said it would retire it along with most other Privacy Sandbox APIs.

Think of it like this

Topics was like a friend telling a shopkeeper, "they seem to be into cooking lately," without revealing where you had been or who you were.

An example

In a 2024 test, a publisher in Italy received topics such as "Cooking & Recipes" and "Football" from Chrome for a visitor, and an SSP passed them to DSPs, which used them to lift bids on relevant campaigns.