The Privacy Sandbox timelineThe Privacy Sandbox proposals are in various stages of development. This timeline reflects when we expect new technologies will be ready to support key use cases, so that Chrome can responsibly phase out third-party cookies. Information may change and will be updated monthly. Last update: September 2021.
Frequently Asked Questions
How often will the timeline be updated?
The timeline will be updated monthly.
Is this the definitive list of technologies Chrome will be supporting?
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.
How firm are the dates on the timeline?
It’s difficult to forecast how long the open, public process for developing a new web technology might take, as the new APIs may receive a lot of feedback or require multiple testing cycles. These extended discussions and testing stages often produce better, more complete solutions, and the timeline for testing and ready for adoption of use cases might change accordingly.
Where can I learn more about the timeline to phase out third-party cookies support in Chrome?
You can read an announcement of this change on the Keyword blog.
Why doesn’t the timeline show all the Privacy Sandbox proposals?
The timeline is specific to key use cases related to Chrome’s plan to phase out third-party cookies. The technologies solving for the second goal of the Privacy Sandbox initiative -- prevent covert tracking -- will follow separate timelines, as noted above.
What does origin trial (“OT”) mean in the timeline?
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.
How can I find out exactly when an origin trial (“OT”) is starting or ending?
Chrome’s origin trial registration page provides information for origin trials that are live or starting soon. Click the “Register” button for an active origin trial to see planned start and end dates. Note, it’s common to extend origin trials when further testing is needed. It is also common for technologies to go through multiple origin trials as they are refined.
Does this timeline reflect when the APIs will be available globally?
The “ready for adoption” milestone reflects when Chrome expects each use case to be supported globally. It is common for testing to begin with a limited population and gradually expand. We are committed to making all of the Privacy Sandbox technologies available for testing worldwide before they launch. For the “testing” stage, certain APIs may be available in limited ways, for example in selected countries.
Is Chrome considering proposals from other members of the web community?
This timeline reflects the use cases Chrome expects to support before phasing out third-party cookies. Many of the proposed technologies shown on the timeline incorporate concepts and feedback from industry and ecosystem stakeholders. We'll continue to engage publicly and review other proposals as we consider the best way to address critical use cases that support the open web ecosystem.
What does "Feature Flag" mean on the timeline?
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.
- Scaled availability for User-Agent Reduction means the fully Reduced UA string is shipping on all Chrome devices. Reduction is planned to begin with Chrome minor version starting in Q2 of 2022. See here for more info on timelines.
- Earliest date of scaled availability represents the earliest date when Gnatcatcher could be made available to sites for broad use on an optional basis.
- This timeline reflects Chrome’s best estimates, as of September 2021, 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.
- 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.
- Stage 1 of the transition period is expected to last nine months. In Stage 2, we will lower third-party cookies’ Time To Live (TTL) based on a timeline we plan to announce during Stage 1. Stage 2 is expected to last approximately three months.
- The transition period 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.