Jump to content

Read the latest update from the Privacy Sandbox team: General availability and supporting scaled testing


Topics is a proposal in the Privacy Sandbox designed to preserve privacy while showing relevant content and ads. The browser will infer a handful of recognizable, interest-based categories based on recent browsing history to help sites serve relevant ads. With Topics, the specific sites you’ve visited are no longer shared across the web, like they might have been with third-party cookies.

How it works

There are two main parts to Topics. First, the API labels each website from a set of recognizable, high-level topics. For example, the browser would match a sports website with the topic "Sports". Then, the browser collects a few of the most frequent topics associated with the websites you’ve visited. These topics are then shared (one new topic per week) with the sites you visit to help advertisers show you more relevant ads, without needing to know the specific sites you’ve visited.

The browser will use a limited set of topics selected from a human-curated, publicly visible list. The list proposed contains around 350 topics to reduce the risk of fingerprinting. Additionally, Chrome aims to maintain a topics list that does not include sensitive categories (i.e. race, sexual orientation, religion, etc.).

You will be able to see the topics and remove any you don’t like, or disable them completely in Chrome Settings.

Frequently asked questions

When sites use Topics, they will receive the topics that the site visitors might be interested in, without needing an individual’s specific browsing history, such as the exact websites they’ve visited, or their identity and behavior on other sites. However, if a site were to use third-party cookies to show you ads, they could monitor your specific browsing history and associate it to your personal identity.

FLoC was Chrome’s initial privacy-preserving proposal to allow companies to show relevant ads to people based on their web browsing activity, without revealing specific sites they visited to any external parties including Google. Chrome experimented with FLoC in 2021 and received valuable feedback from regulators, privacy advocates, developers and industry. The new Topics API proposal addresses the same general use case as FLoC, but takes a different approach intended to address the feedback received for FLoC. Chrome intends to experiment with the Topics API in 2022 and is no longer developing FLoC.

The technology is still in the early stages of development. The results of the trials and feedback from the web community will inform the timeline.

Chrome is committed to global testing of the technologies which will need to be in place so it can responsibly phase out support for third-party cookies. Chrome aims to roll out API testing globally, including in the EEA and UK.

In Chrome settings, you will be able to find which topics have been generated based on your recent browsing history. You will be able to block specific topics or opt out of the Privacy Sandbox technologies completely.

Chrome will share the list of topics publicly and expects it will evolve over time with the ecosystem feedback.

As Topics uses a recognizable and human-curated list of topics to help infer what ads you will see, Chrome can and will take steps to avoid topics that might be sensitive (i.e. race, sexual orientation, religion, etc.). However, it is still possible that websites calling the API may combine or correlate topics with other signals to infer sensitive information, outside of intended use. Chrome will continue to investigate methods for reducing this risk.

First, Chrome determines the topics associated with websites. For example, a yoga website might be classified as being related to "Fitness". These topics are assigned to the websites themselves, not you. Then, Chrome keeps a handful of your most frequently visited topics in a given week, and participating sites show you ads based on these topics.

The calculation of the most frequent topics occurs entirely within the browser, without sharing data with external servers. The resulting topics may be sent to servers in an anonymous way for sensitivity and abuse analysis.

Yes. Only sites that are using Topics or have at least one embedded service that uses the Topics API, will be included in topics generation. Sites can also specifically opt-out using Permission Policy, an existing browser mechanism that is used to control features like camera access.

If a website had opted out of FLoC, the Topics API will respect that decision.

The article "What is the Topics API?" on developer.chrome.com is a good start, you can also read a full technical explainer.