The first phase of Google’s long-standing plan to kill third-party cookies in Chrome is nearly complete. Following Chrome 115’s public release on July 18th, Google says that it will gradually begin enabling the Privacy Sandbox toolkit for Chrome developers set to replace third-party tracking cookies with privacy-preserving API alternatives.

There are still several stages to go until Google completes its Privacy Sandbox rollout, but shipping these APIs is a significant milestone toward the company’s goal of phasing out third-party cookies entirely. Google is still aiming to enable an opt-in testing mode that will allow advertisers to experiment with the Sandbox tools without cookies by late 2023 and to turn off third-party cookies for 1 percent of Chrome users sometime in Q1 2024. The company has set a goal to completely turn off third-party cookies by Q3 2024.

You can read specific details about the new “relevance and measurement” APIs on the Chrome Developers blog for Chrome 115. These include the Topics API that categorizes a user’s interests based on their web usage without sharing the information directly with advertisers, the Attribution Reporting API that measures when ad clicks or views lead to conversions, and the Protected Audience API (previously called FLEDGE), which allows relevant ads to be displayed to users based on their previous interactions with the advertiser.

The APIs will initially be switched on for a limited number of Chrome developer browser instances, which will gradually increase as the rollout progresses to allow Google to monitor any potential issues. Similarly, only some Chrome developers will have all of the available APIs enabled during this rollout — a few groups will only see a subset of the new APIs activated so that it’s easier to detect and isolate issues with specific APIs.

Google says this process will likely begin next week, starting July 24th, and that it intends to enable the APIs for around 35 percent of browsers over the course of the week. By the start of August, the company is aiming to scale this to 60 percent, with the goal of enabling APIs for 99 percent of Chrome 115 browsers around the same time that Chrome 116 is expected to be generally available in mid-August. By this point, Google says most of the earlier limited access testing groups should have all of the relevance and measurement APIs enabled, with the company planning to maintain “only small, isolated groups” without every API enabled.

Google originally projected it would phase out third-party cookies in late 2023, though various onboarding issues and regulatory investigations have delayed the project. The UK’s Competition and Markets Authority (CMA), which previously expressed concerns that the new approach may unfairly benefit the search giant’s own advertising business, published its guidance for third parties testing Google’s Privacy Sandbox tools in June. Google’s plans passed the CMAs regulatory hurdles back in 2022 (provided Google sticks to the list of commitments it made to get approval), and the company said it “will continue working closely with the CMA” before taking any further step to stop third-party cookies for good.