How Ad Tech Might Work in a Post-Cookie World

The back-and-forth of Google’s Chrome Privacy Sandbox proposals

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Dovekey proposes an external 'key value server,' granting a degree of autonomy from Google. Trent Joaquin/Google

Key Insights

Despite the chaotic mess that has been 2020, Google announcing plans to withdraw support for cookies in Chrome is still ad tech’s biggest story.

The move reflects how laws such as the General Data Protection Regulation and the California Consumer Protection Act are curbing online user targeting.

Arguably, Apple’s intelligent tracking prevention (ITP) rollout, beginning in 2017, was a harbinger of how this societal shift was to force the hand of major platform providers in implementing cataclysmic changes that would impact the online ad industry. And given Chrome’s market share, the disruption caused by ITP will be magnified greatly come 2022.

The ‘cookie-pocalypse’ countdown

In January 2020, Google announced a two-year countdown before it will cease supporting third-party cookies, the common currency for the online ad industry, in its Chrome web browser, a move that prompted much existential dread.

Execs at IAB Tech Lab who had seen the writing on the wall since the debut of ITP quickly attempted to convene “Project Rearc” in an attempt to establish a new modus operandi for the $565 billion industry, a feat that would require an unprecedented degree of consensus, not to mention public education.  

Privacy Sandbox

Simultaneous to its 2022 announcement, Google’s Chrome browser team—an important distinction—announced Privacy Sandbox to replace pre-existing cross-site tracking technologies.

Instead of cookies, it proposed the ad industry use aggregated data based on anonymized identifiers, or APIs, to assess ad performance, like these:

  • Trust Tokens – An anonymous means to verify traffic is generated by a user, not a bot
  • Click Through Measurement – An alternative to cookies to help measure conversions
  • Federated Cohort Learning – Software to study the habits of similar user groups
  • Private Interest Groups, Including Noise (PIGIN) – A means for advertisers to track interest groups

The key element of the proposal was that all auction decisions would take place in the browser rather than in a third-party ad server.

Buy-side sources questioned how critical trading functions like frequency capping and brand safety would work in such an environment. Some feared this was a case of the dominant becoming more powerful.

Deliberations via W3C   

Adweek first reported on plans to kill third-party cookies in March 2019 when Google sources spoke of its wariness over antitrust concerns. These are coming to a head to the extent that it set up distinct working groups to deliberate the future.

Hence, Google has been at pains to make details of Privacy Sandbox available via open-source forums such as GitHub with the proposals also debated at web standards body W3C. Here, the practicalities of such proposals are open to peer review.

Privacy Sandbox’s PIGIN proposal was initially poorly received, and effectively, is now off the slate.

Google’s own advertising team, distinct from the Chrome browser team, subsequently proposed a set of standards named Turtledove, which aimed to reconcile privacy concerns over PIGIN.

Essentially, it proposed the software that would derive what “interest group” online audiences belong to, generated within the Chrome browser.

Advertisers bidding on a particular ad impression would be unable to combine that information with other datasets, meaning third parties, and publishers, wouldn’t be able to glean as much information on a website user as in the past.


@andrewblustein andrew.blustein@adweek.com Andrew Blustein is a programmatic reporter at Adweek.
@ronan_shields ronan.shields@adweek.com Ronan Shields is a programmatic reporter at Adweek, focusing on ad-tech.
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