We are deprecating third-party cookies in the second half of 2024, full stop.”―Joey Trotz, Director of Product for Privacy Sandbox Ecosystems“

The deadline for phasing out third-party cookies from Chrome is approaching, and Google has no intention of further delaying it. Even the UK's Competition & Market Authority, a regulator that many believed could affect the timeline, indicates in its reports that Google is meeting all commitments and that the transition in 2024 will go ahead as planned.

Originally, in early 2020, shortly after the announcement of the Privacy Sandbox, Google declared its plans to phase out third-party cookies from Chrome in 2022. The withdrawal date was quickly changed to 2023, and in mid-2022 Google pushed the date to mid-2024 promising that this will be the final date. One year later, this bears out, and is strongly indicated by all the developer steps that Google is now taking to secure all possible aspects of such a massive change. 

General Availability―The First Big Step

The Privacy Sandbox includes multiple APIs, with three being especially critical for the initiative―Protected Audience API, Topics API, and Attribution Reporting API. According to the latest announcement, with the launch of the stable version of Chrome 115 in mid-July this year, the General Availability of most of these tools will begin. But what does General Availability even mean? This means that the APIs are available to all users by default in Chrome, without requiring browser flags or participation in an origin trial. This will allow for scalable live-traffic-based testing in preparation for the complete phasing out of third-party cookies a year later. Google also promises that these APIs will not change much during this time.

Experiment Labels To Help With Simulations

Following the General Availability announcement, Chrome has prepared two test modes that will be available in the coming months. Mode A, expected in Q4 2023, is called ‘opt-in testing.’ Ad tech vendors will have the possibility to set experiment labels for a specific portion of Chrome traffic. This allows advertising companies to coordinate with each other, if they choose to, in order to conduct Protected Audience auctions without relying on third-party cookies. The purpose of this is to maintain consistent experiment groups. They can also use these labels for their own independent experiments and testing. It's important to note that Chrome will not make any changes to the state of third-party cookies for users in Mode A. It will allow the industry to test with an increased volume of traffic, but it won’t permit the meaningful measurement of cookieless solutions performance, as they still have to operate in a cookie-based environment.

First Cookieless Tests of Privacy Sandbox―Q1 2024

The second mode of testing, Mode B, in which 1% of Chrome users will no longer have third-party cookies, is planned for Q1 2024. This change will be implemented globally and does not require user opt-in. In addition, within Mode B, Chrome plans to disable Privacy Sandbox relevance and measurement APIs for a small fraction of traffic. However, other APIs, like First-Party Sets, CHIPS, FedCM, and others, will remain functional. This combination is aimed at establishing a performance baseline without third-party cookies, and feedback is being sought regarding the appropriate percentage of traffic for this subset of testing.

It is also important to note that certain site features may be affected if the site has not yet adoted alternative solutions like CHIPS or First-Party Sets. To address any issues that impact user experience during this phase, efforts are being made to detect, address, and proactively notify site owners.

Tests Are Essential for a Smooth Transition

The forms of testing outlined above are intended to meaningfully, both quantitatively and qualitatively, evaluate cookieless targeting technologies. They aim to answer questions about both functional and performance aspects of these tools. Broad participation in these tests is critical as it will be the last chance before cookie deprecation to report potential issues to Google. If there are no critical issues, or if Chrome manages to resolve them all by Q3 2024, Google will begin phasing out third-party cookies for all users. 

Considering all the facts presented above, it can be concluded that this is one of the last moments to start paying attention to Privacy Sandbox-related solutions. The deprecation of third-party cookies will definitely happen, and it will mark an entry into a completely new world for the advertising industry. Now is the time to reconsider partnerships and/or allocate resources to prepare for testing solutions in a cookieless environment. Our advice is to seize the day so as not to wake up at the wrong time with non-functioning products and services.

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