With FLoC In The Rearview, Google Will Test FLEDGE And Phase 2 Attribution Reporting

Google will starting testing its FLEDGE and Core Attribution reporting APIs in the Privacy Sandbox during the first half of this year (2022).

The Privacy Sandbox is bursting with news this week.

On Thursday, Google shared a slightly more concrete testing timeline for its FLEDGE and Core Attribution reporting API. Two days before, on Tuesday, Google announced the Topics API, a new proposal for post-cookie interest-based advertising that now replaces FLoC.

Google, which teased earlier this week that more info about FLEDGE and measurement was shortly forthcoming, confirmed that it will open up FLEDGE testing for the first time during the first half of this year, and also begin the second phase of testing for its attribution reporting API.

FLEDGE was supposed to have begun testing during Q4 2021 but in October the program was pushed back to early this year.

Google already ran initial origin trials during Q1 2021 for its attribution reporting API, which measures when a user’s actions, like an ad click or a view, leads to a conversion without using cross-site IDs.

You can stay up-to-date on the Privacy Sandbox testing timeline here.


FLEDGE, which stands (somewhat torturously) for “first locally-executed decision over groups experiment,” is the Privacy Sandbox’s answer to retargeting. The purpose is to allow remarketing to brand-specific cohorts of users without allowing third parties to track browsing behavior across sites.

It’s an evolution of Google’s TURTLEDOVE proposal, which (very torturously) stood for “Two Uncorrelated Requests, Then Locally-Executed Decision On Victory.”

(Maybe it’s a good thing that the naming convention for Privacy Sandbox proposals is graduating from the aviary.)

The attribution reporting API or, more officially, the Core Attribution API, is meant to support view-through and click-through conversions.

The second origin trial for attribution reporting, which is also scheduled to start during the first half of the year, will include enhanced testing and debugging methods so that companies can more easily analyze their results compared to existing third-party cookie-based measurement.

All together now

No API proposal in the Privacy Sandbox recreates the full functionality of third-party cookies on its own.

Topics will be for targeting, FLEDGE will be for retargeting, Core Attribution is for measurement – etcetera.

And so, in addition to testing each separately, eventually it will be necessary to test them all together to see how they work in tandem. The vision is that they’ll be used in conjunction with one another.

Google, for example, anticipates advertisers will use FLEDGE and the Topics API together to decide which ad to show a user, explained Ben Galbraith, who leads product for Google Chrome’s web platform, speaking with AdExchanger during a previous interview. Advertisers that have their own first-party information about a user, meanwhile, may rely on that data for targeting.

Trust tokens, part of another Privacy Sandbox API, are necessary to help combat spam and fraud without fingerprinting, he said, but advertisers will also need a privacy safe way to attribute campaigns after third-party cookies are gone.

“All of these signals together give the advertiser the option to choose which makes sense to produce the most relevant result,” Galbraith said, “ … [and] provide the ability for us to move the ecosystem away from third-party cookies and other tracking techniques while ensuring that all of these use cases are preserved and ultimately more private for users.”

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