Updated Jan 25th 2022: As of this date Google has announced that FLoC is no more. In its place is the Google Topics API. You can read the full API readme here, but in short...

"The intent of the Topics API is to provide callers (including third-party ad-tech or advertising providers on the page that run script) with coarse-grained advertising topics that the page visitor might currently be interested in. These topics will supplement the contextual signals from the current page and can be combined to help find an appropriate advertisement for the visitor."


Since this blog post was published, Google has announced that it is pushing back the final deadline for its phasing out of third-party cookies to late-2023.

For an up-to-date look at the death of third-party cookies, don't miss our comprehensive guide to life after third-party cookies...


Post-Cookie Advertising: What is FLoC?

The death of the third-party cookie is something we’ve been talking about for over a year. While Google was sure it would be phasing out the outdated tracking mechanism - Google Analytics 4 is designed to adapt to life without cookies - it hadn’t announced what the privacy-first future of ad targeting would look like.

Now we have a clearer idea.

While we’ve known about FLoC for some time, Google has announced via a blog post from Group Product Manager, User Trust and Privacy, Chetna Bindra, that “advertisers can expect to see at least 95% of the conversions per dollar spent when compared to cookie-based advertising.”

Against a backdrop of cookie-less advertising resulting in a 52% reduction in revenue and you can see why the internet is ablaze with news of Google’s finding. It would appear a privacy-first internet can satisfy both advertisers and the end-user.

What is FLoC?

FLoC stands for Federated Learning of Cohorts. A privacy-first alternative to third-party cookies, it clusters large groups of people with similar interests together, hiding individuals “in the crowd” and uses “on-device processing” to keep everyone’s browsing history private.

Currently, tracking relies on understanding the specific sites or pages visited by a user. This is achieved by third-party cookies and, in some cases, potentially unscrupulous device fingerprinting. This is not good for privacy.

Instead, FLoC works by enabling browsers - Chrome, in this case - to understand the websites a user is visiting and algorithmically place them into a cohort. These cohorts, large enough to obfuscate the individual, can then be used for ad targeting.

The idea is that all information provided to the cohort-sorting algorithm is kept local and not uploaded elsewhere. The browser simply reveals the cohort, protecting the user.

When Will FLoC be Available?

According to Google, FLoC-based cohorts will be made publicly available via origin trials alongside Chrome’s next release in March 2021.

More importantly (for us), is news that Google will begin testing cohorts with advertisers in Google Ads in Q2 2021.

A Word of Caution

Google has, understandably, been quick to issue a word of caution alongside this announcement. FLoC is still relatively early in testing and isn’t the only privacy solution being tested as part of Chrome’s Privacy Sandbox.

Also being tested are privacy solutions across key areas like “fraud detection, the tailoring of content, first-party treatment of a company’s owned and related domains, ads measurement, and a private-by-default way to request browser info.”

Furthermore, Chrome users will soon start to see changes as privacy features are rolled out. This will begin in April when end-users will be given the option to decide whether or not content is tailored to them via the Privacy Sandbox.