What Is the Topics API and How Chrome Categorizes Your Interests
Patrick Bushe
March 20, 2026 · 5 min read
The Topics API was Google's proposed replacement for one use of third-party cookies: showing ads based on your interests. Instead of trackers following you across sites, Chrome itself guessed your interests and shared a few broad topics with sites. In October 2025, Google announced it was retiring Topics along with most of its Privacy Sandbox advertising APIs.
How it worked
- Chrome matched the sites you visited to topics from a fixed list of a few hundred, such as "Fitness" or "Travel".
- Each week, it worked out your top topics from your browsing, on your device.
- When a site or ad service using the API asked, Chrome shared a small number of topics from recent weeks, but only topics that service had already seen you browse.
- Sometimes it shared a random topic instead, to make the data less precise.
- Topics were kept for a few weeks and then deleted.
The list left out sensitive categories, such as health conditions, religion and sexual orientation, though critics noted that combinations of ordinary topics can still reveal a lot.
Why it was controversial
- Privacy groups said it was still interest-based tracking, just done by the browser.
- Other browsers, including Firefox and Safari, declined to support it.
- Advertisers said it was less effective than cookies, and adoption stayed low.
- Regulators examined whether it gave Google an unfair advantage in advertising.
Why it's being retired
Google had planned to remove third-party cookies from Chrome and replace them with Privacy Sandbox tools. In 2025 it decided to keep third-party cookies, and in October 2025 it announced it would retire Topics and most of the other advertising APIs because of low adoption. See the third-party cookie timeline.
How to check or turn it off
Go to Settings → Privacy and security → Ad privacy. Depending on your Chrome version, you'll see Ad topics, where you can view and remove topics or switch the feature off. If the setting is gone, your version no longer uses it.
What still tracks your interests
With Topics going away and third-party cookies staying, the familiar methods remain:
- Third-party cookies. Block them in Settings → Privacy and security → Third-party cookies.
- Browser fingerprinting. See fingerprinting explained.
- Your Google account's own ad settings, at myadcenter.google.com.
A tracker blocker cuts most of this off. Ghost Browser takes a different approach, visiting random sites in the background so any interest profile built from your browsing is less accurate.
