Note d'experts

Privacy Sandbox: Changes Coming to Google Chrome

Mathieu Lima
Mathieu Lima
Mis à jour : 26 nov. 20255 min read

TL;DR

  • Google is introducing new Privacy Sandbox features for Chrome to protect user privacy online while enabling businesses to grow their digital activity.
  • The new features allow managing privacy settings for ads, recording user interest topics, limiting covert tracking, and measuring ad performance.
  • Google aims to phase out third-party cookies for Chrome in the first half of 2025, but first-party cookies will remain functional. More details in our expert note dedicated to the end of third-party cookies for Chrome.

Privacy Sandbox: What Is It?

A Google-Led Initiative

The Privacy Sandbox initiative was initiated by Google and aims to create technologies that protect user privacy online while giving businesses and developers the tools needed to grow their digital activity. It aims to reduce cross-site tracking (notably by progressively eliminating third-party cookies) and cross-app tracking, while preserving free online content and services for everyone.

The solutions being developed by Google and other contributors to this initiative aim to limit individual tracking and offer alternatives that will replace current technologies while keeping them relatively open (Google's advertising solutions will be the first to benefit) and accessible to all.

Measures to restrict or remove existing mechanisms, such as third-party cookies, have already been taken in recent years on other browsers like Safari and Firefox (with ITP and ETP). Google wants to move in this direction while proposing alternatives, notably allowing businesses to continue presenting relevant ads to their users, without requiring online tracking identifiers.

Privacy Sandbox for the Web

The Privacy Sandbox initiative concerns two platforms: Chrome for the Web and Android for Apps. On Chrome, one of the main objectives for users is to make third-party cookies obsolete by notably using protection techniques such as differential privacy, k-anonymization, and on-device processing. The other main objective for users is to limit covert tracking like fingerprinting, by limiting the amount of information sites can access so that user information remains private, safe, and secure.

Google aims to phase out third-party cookies in Chrome in the second half of 2024, as is already the case for Safari and Firefox. This doesn't mean all cookies will be unusable: first-party cookies will remain fully functional and will still allow, for example, analyzing visitor behavior on your preferred audience measurement tool.

July 2023: New Advertising Settings Available on Chrome

Since early July 2023, Google has been progressively integrating new features directly related to Privacy Sandbox into Google Chrome. This is notably the case since version 115 of the browser with the introduction of Privacy Sandbox Settings V4 and the first Privacy Sandbox Ads APIs.

Directly accessible from Chrome browser settings, in the Privacy and security menu, a new section is available to manage privacy settings for ads: Ads privacy.

Several settings are possible:

  • Ad topics (using the Topics API): to personalize the advertising experience, Chrome records the user's interest topics based on browsing history: visited sites and frequency at which they are visited. The browser can share up to three interests at a time with sites and automatically removes interest topics older than 4 weeks. Users can block topics they don't want to share with sites in this section.
  • Site-suggested ads (also using the Topics API): a visited site can recommend and store ad suggestions for products or services that might interest the visitor. As browsing continues, ads may be displayed based on suggestions from similar sites. Chrome automatically removes suggestions older than 30 days, but they could reappear if the user visits the site again. Users can also block certain sites in this section: all associated ad suggestion data will be deleted and these sites will no longer store ad suggestions with Chrome.
  • Ad measurement (using the Attribution Reporting API): Chrome can share with advertisers a limited amount of cross-site data to measure their ad performance. Browsing history is kept only on the user's browser and reports are sent with a certain delay to protect user identity. If ad measurement is enabled in Chrome and on the user's Android device, a business may be able to measure the effectiveness of an ad across visited websites and used apps. If browsing history is deleted by the user, this also deletes ad measurement data.

Since July 2023, different popups are displayed when launching the Chrome browser depending on the user's region, especially if they are in Europe.

These popups are both informative and allow making choices regarding the activation of different available Privacy Sandbox features on the Web.

Other Privacy Sandbox Features on the Web

Here is the list of all known features and APIs to date for Privacy Sandbox on the Web, by purpose:

Fight spam and fraud on the web

  • Private State Tokens API

Display relevant ads and content

  • Topics API (replacing FLOC)
  • Protected Audience API (formerly FLEDGE)

Measure ad performance

  • Attribution Reporting API (formerly Conversion Measurement API)

Fight cross-site and covert tracking

  • First-Party Sets API
  • Shared Storage API
  • CHIPS API
  • Fenced Frames API
  • Federated Credential Management API
  • IP Protection
  • Privacy Budget
  • Network State Partitioning
  • User-Agent Reduction
  • Storage Partitioning
  • Bounce Tracking Mitigations
  • User-Agent Client Hints API
  • DNS-over-HTTPS auto-upgrade

Privacy Sandbox Development

Privacy Sandbox technologies have been in development for several years now. Google communicates on a timeline for these features, accessible here and regularly updated.

For more details, Google also regularly communicates on the Chrome developer blog, with many details on features and new developments.

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