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Read case studies from companies helping to shape the future of online privacy, or learn more about the Privacy Sandbox technologies in our developer documentation.
Privacy Sandbox for the Web
Privacy Sandbox for the Web provides open-source, privacy-enhancing technologies that empower businesses to thrive while respecting user privacy. By reducing reliance on various forms of tracking, we're building a web where companies can achieve their goals and people’s information stays private and secure.
Privacy Sandbox Timeline for the Web
The Privacy Sandbox proposals are in various stages of the development process. This timeline reflects when we expect new privacy-preserving APIs and other technologies to be ready in support of key use cases. Information may change and will be updated monthly.
The proposals are being developed in public forums, in collaboration with members of the industry. We also continue to work with the UK's Competition and Markets Authority in line with the commitments we offered for Privacy Sandbox for the web. We encourage participation through the many public feedback channels that inform development of the proposals. Stakeholders can also use this form to share feedback directly with Chrome.
Last Update: July 2025
Third-Party Cookies (3PC) and Testing
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Opt-in Testing with Labels Chrome will provide developers an experiment label for independent testing and simulation of third-party cookie deprecation.
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1% 3PC Deprecation Chrome will deprecate third-party cookies for 1% of Chrome users globally.
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Third-Party Cookie Phase Out * We envision proceeding with third-party cookie deprecation starting early 2025, subject to resolving any remaining concerns with the CMA.
- 2021
- 2022
- 2023
- 2024
Third-party cookies phases: Opt-in testing with labels: Q4 2023 through Q3
2024; 1% Third-party cookies deprecation: Q1 2024 through Q4 2024;
Third-party cookies phase out: Q1 2025
Timeline update pending
Please read our July 2024 announcement for an important update regarding third-party cookies in Chrome.
Timeline update pending
Please read our July 2024 announcement for an important update regarding third-party cookies in Chrome.
* Subject to resolving any remaining concerns with the CMA.
The Privacy Sandbox APIs
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Discussion The technologies and their prototypes are discussed in forums such as GitHub or W3C groups. Some limited testing of solutions might happen at this stage to facilitate discussions.
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Pre-Launch Testing The technologies for the use case are available for testing via Chrome origin trials or other pre-launch methods. Changes may be made based on testing results and ecosystem feedback.
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General Availability The technologies for the use case are launched and available for 100% of Chrome traffic. Chrome expects refinements and optimizations as more companies test and use the APIs over time.
- 2021
- 2022
- 2023
- 2024
Fight spam and fraud on the web
Fight spam and fraud on the web proposals phases: Testing period: Q1 2021
through the end of Q3 2022; Transition period, stage 1: Q4 2022 through the
end of Q2 2023; Transition period, stage 2: Q3 2023.
- OT STARTED Private State Tokens API: The origin trial has been open since Q3 of 2020. Register Now
- OT CLOSED Private State Tokens API: The origin trial for Private State Tokens API ran from Chrome 84 - 101.
Show Relevant Content and Ads
Show relevant content and ads proposals phases: Discussion period: Q1 2021
through the end of Q4 2021; Testing period: Q1 2022 through the end of Q3
2022; Transition period, stage 1: Q4 2022 through the end of Q2 2023;
Transition period, stage 2: Q3 2023
- OT STARTED Topics API: The origin trial for Topics API was announced in Q1 2022 and started in April 2022. Register Now
- OT CLOSED Topics API: The origin trial for Topics API ran from Chrome 101 to 115.
- FEATURE FLAG Protected Audience API: The feature flag is available from Chrome 91. Read More
- OT STARTED Protected Audience API: The origin trial for Protected Audience API was announced in Q1 2022 and started in April 2022. Register Now
- OT CLOSED Protected Audience API: The origin trial for Protected Audience API ran from Chrome 101 to 115.
Measure digital ads
Measure digital ads proposals phases: Discussion period: Q1 2021 through the
end of Q4 2021; Testing period: Q1 2022 through the end of Q3 2022;
Transition period, stage 1: Q4 2022 through the end of Q2 2023; Transition
period, stage 2: Q3 2023
- OT STARTED
- OT CLOSED Attribution Reporting API: The first origin trial for the Attribution Reporting API ended on January 25, 2022. Read more
- OT STARTED Attribution Reporting API: The second origin trial for Attribution Reporting API, which includes support for aggregate measurement and view-through conversions, was announced in Q1 2022 and started in April 2022. Register Now
- OT CLOSED Protected Audience API: The origin trial for Protected Audience API ran from Chrome 101 to 115.
Strengthen Cross-site Privacy Boundaries
Strengthen Cross-site Privacy Boundaries proposals phases: Discussion
period: Q1 2021 through the end of Q1 2022; Testing period: Q2 2022 through
the end of Q3 2022; Transition period, stage 1: Q4 2022 through the end of
Q2 2023; Transition period, stage 2: Q3 2023.
- FEATURE FLAG Related Website Sets API: The feature flag is available from Chrome 89. Read More
- OT STARTED
- OT CLOSED Related Website Sets API: The origin trial for FPS ran from Chrome 89-93.
- FEATURE FLAG Related Website Sets API: The feature flag is available from Chrome 108. Read More
- OT STARTED Shared Storage API: The Origin Trial has been open since Q2 of 2022. Register Now
- OT CLOSED Shared Storage API: The origin trial for Shared Storage API ran from Chrome 101 to 115.
- OT STARTED CHIPS API: The origin trial has been open since Q1 of 2022. Register Now
- OT CLOSED The origin trial for CHIPS ended in Chrome 106. CHIPS will start rolling out to Chrome stable in February 2023.
- OT STARTED Fenced Frames API: The Origin Trial has been open since Q2 of 2022. Register Now
- OT CLOSED Fenced Frames API: The origin trial for Fenced Frames API ran from Chrome 101 to 115.
- OT STARTED Federated Credential Management API: The Origin Trial has been open since Q2 of 2022. Register Now
- OT CLOSED Federated Credential Management API: The origin trial for Fed CM ran from Chrome 101-107. Federated Credential Management API is now shipping to 100%. Read More
The Privacy Sandbox initiative also includes efforts designed to limit covert tracking. These include proposals that address specific covert tracking techniques such as fingerprinting and network-level tracking.
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Early Phases
Proposals go through an early incubation phase before moving into development.
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In Development
These proposals are currently in development and/or being tested. Learn more about the implementation details of each proposal by clicking on the links below.
IP Protection -
Launched
These proposals are available by default in Chrome stable. Learn more about the implementation details of each proposal by clicking on the links below.
Network State Partitioning
User-Agent Reduction
User-Agent Client Hints API
DNS-over-HTTPS auto-upgrade
Storage Partitioning
Bounce Tracking Mitigations
Privacy Sandbox Proposals for the Web
Topics API
Topics API enables businesses to show relevant ads based on broad interest categories, like sports or travel, without relying on third-party cookies or individual tracking. The browser infers these interests, known as “topics,” from recently visited sites without surfacing a person’s specific browsing information.
Protected Audience API
Protected Audience API helps businesses re-engage audiences who have previously shown interest in their products or services, without exposing their personal information. Companies can create anonymized custom audiences based on website visitors’ on-site behavior. Marketers then bid to show relevant ads to re-engage these audiences, all without relying on individual tracking.
Attribution Reporting API
Attribution Reporting API allows businesses to measure ad campaign effectiveness, like understanding which ads led to purchases, without relying on third-party cookies or identifying people at an individual level. It provides reports that match ad interactions with conversions, delivering effective insights while respecting user privacy.
CHIPS
CHIPS (Cookies Having Independent Partitioned State) maintains embedded site functionality by providing access to specific compartmentalized information, without enabling tracking.
Fenced Frames
Fenced Frames protects embedded content, as a replacement for an iframe, so it can't pass the embed data back to the site that embedded the fenced frame. The result is the data within the fenced frame is isolated, and no user activity is shared or stored.
FedCM
Federated credentials allow people to sign in to various sites using their existing logins from Identity Providers, like social logins. This process enhances security and convenience for people while streamlining login management for businesses.
User-Agent Client Hints
User-Agent Client Hints API enables sites to request relevant information about a user’s browser to address certain use cases, rather than have it shared passively via the User-Agent header.
User-Agent Reduction
User-Agent (UA) reduction is the effort to minimize the identifying information shared in the User-Agent string which may be used for passive fingerprinting.
DNS-over-HTTPS
DNS-over-HTTPS is a protocol that encrypts Domain Name System (DNS) queries and responses by encoding them within HTTPS messages. This helps prevent attackers from sending users to phishing websites or observing what sites they visit.
IP Protection
IP Protection is the Privacy Sandbox’s proposal to hide IP addresses, in Chrome’s Incognito mode, from third-party sites known to track users.
Storage Partitioning
Storage Partitioning will isolate some web platform APIs used for storage or communication if used by an embedded service on the site, i.e., in the third-party context. This helps maintain web compatibility with existing sites while enhancing privacy and security.
Storage Access API
Storage Access API enables third parties to share information across sites only when user interaction and permission requirements are met, preventing unwanted tracking.
Network State Partitioning
Network State Partitioning reduces the sharing of network-related caches and state (i.e., shared DNS cache, socket reuse, etc.) in order to limit the ability to track users across first-party contexts.
Bounce Tracking Mitigations
Bounce Tracking Mitigations reduce or eliminate the ability to track users via redirects as they navigate across the web.
Private State Tokens
Private State Tokens protect sites from bots and fraudulent traffic by using the browser to convey user trust signals, without revealing that person’s information.
FLoC API
FLoC was a Privacy Sandbox proposal designed to cluster people with similar browsing patterns into large groups, or "cohorts". This "safety in numbers" approach was designed to effectively blend any individuals into a crowd of people with similar interests. The development of FLoC stopped in 2021.
Privacy Budget
Privacy Budget was a proposal that restricted the amount of identifying information that a site is allowed to access, in order to help prevent the user from being uniquely identifiable. The Privacy Budget is no longer an active proposal as of January 2024.
Frequently Asked Questions
Not necessarily. Chrome is focused on developing proposals that support key use cases. The set of proposals solving for a particular use case (for example, showing relevant content and ads) may change and evolve over time, with web community feedback and testing. The APIs shown on the timeline are based on current expectations and might change.
Origin trials are one method of testing new web technologies in Chrome. "OT" labels are shown when a Chrome origin trial has been publicly announced, is in progress, or has concluded. We will add new origin trials, and other forms of available testing, on the timeline as part of the monthly updates. Chrome's origin trial registration page provides information for origin trials that are live or starting soon.
While features are in development they are often made available behind one or more temporary flags (off by default) that can be used to enable and configure their behavior for local developer testing purposes. This may be as command line flags that need to be passed in when launching Chrome or as options in the chrome://flags browser interface.
Chrome works with a broad group of stakeholders throughout the web ecosystem – including web browsers, online publishers, ad tech companies, advertisers, developers, and users – to inform the design and implementation of the Privacy Sandbox technologies. Additionally, Chrome continues to work with regulators, including the UK's Competition and Markets Authority in line with the commitments offered for the Privacy Sandbox for the Web.
We want people to be aware of what's changing and how the changes offer more control over how your data is used in the ads you see. Some users may not be familiar with the term Privacy Sandbox, and “ad privacy” is a straightforward way to describe these controls.
All users will have robust controls, and can opt out of Privacy Sandbox relevance and measurement technologies at any point. You can learn more about controlling your ad privacy in Chrome here.
Privacy Sandbox technologies enhance user privacy by enabling companies to select and measure ads without identifying or tracking individual users across sites and without relying on third-party cookies. Users may not notice immediate changes in the advertising they see, but they will have new controls and gain more insight into how companies can use Privacy Sandbox technologies to deliver and measure the ads they see (more information).
- This timeline reflects Chrome’s best estimates, as of July 2025, of the timing of the key Privacy Sandbox use cases, including the availability of origin trials, readiness at scale of the listed APIs, and ending support for third-party cookies. Dates are subject to change. Chrome will update this timeline monthly with current estimates.
- General Availability will start once APIs for all of the use cases are ready for scaled adoption. Chrome will announce the start of the transition period on this site and on the Keyword blog.
- The timeline lists the use cases that Chrome plans to support before the transition period: Fighting spam and fraud on the web; Measuring digital ads; Showing relevant content and ads; Strengthening cross-site privacy boundaries. The APIs listed under each use case reflect Chrome’s current proposals to support this use case. The specific APIs are subject to change.
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