Google plans to roll out the new technology to replace third-party cookies in April after early tests indicated the initiative is just as effective for user tracking and advertising. There is still some concerns as to how Federated Learning of Cohorts would actually improve user privacy.
Third-party cookies are used by website advertisers and partners and can be used to track a user’s Internet browsing behavior across different sites. Apple and Mozilla block third-party cookies by default in their browsers (Safari and Firefox) to improve user privacy, and Google said it will phase them out over two years as part of its Privacy Sandbox initiative. Privacy concerns about user tracking has been growing—especially with third-party data being bought and sold on data exchanges—but Google’s position has been that there has to be an alternative because the advertising industry isn’t going away. Businesses need advertising to grow their business, and tech companies need ad revenue.
FLoC will “help publishers and advertisers succeed while also protecting people’s privacy as they move across the web,” Chetna Bindra, Google's head of user trust and privacy for advertising, wrote in an update.
The FLoC API would use machine learning algorithms to analyze the user’s browsing history (as collected by the browser) and organize the users into large demographic groups (cohorts). The browsing history remains on the device, and the group-data is what gets shared with advertisers rather than individual identifiers. Details of individual users would be hidden from advertisers so theoretically, one person would be indistinguishable from others in the same cohort.
FLoC “hides individuals ‘in the crowd’ and uses on-device processing to keep a person’s web history private on the browser,” Bindra said.
Preliminary tests showed this method is an “effective replacement,” as advertisers can expect to see “at least 95% of the conversions per dollar spent when compared to cookie-based advertising,” Bindra said.
From a privacy perspective, Google hasn’t won over the critics yet, despite touting the privacy benefits to its proposals. The Electronic Frontier Foundation called FLoCs the opposite of privacy-preserving technology” a year ago. Discriminatory advertisers could potentially use the cohorts to identify and filter groups representing vulnerable populations.
“A flock name would essentially be a behavioral credit score: a tattoo on your digital forehead that gives a succinct summary of who you are, what you like, where you go, what you buy, and with whom you associate,” EFF staff technologist Bennett Cyphers wrote. “The flock names will likely be inscrutable to users, but could reveal incredibly sensitive information to third parties.”
The latest update didn’t do much to allay privacy concerns beyond promising “viable privacy-first alternatives.” It isn’t clear how—or if it is even possible—to measure how much more privacy users could expect with the new technology than the current regime.
Advertisers have also been skeptical, arguing that deprecating third-party trackers could hurt online competition because it would force advertisers to spend more on Google’s tools. The United Kingdom’s Competition and Markets Authority (CMA) is investigating Privacy Sandbox after a coalition of digital marketing companies and others from newspapers and technology companies complained Google was abusing a dominant position (the fact that Chrome is the most widely used browser) by depreciating support for third-party trackers. Google’s proposals would impact independent media owners and small local publishers as they would be cut out of the open online marketplace, Marketers for an Open Web (MOW), the coalition pushing the complaint.
Google is working on multiple proposals as part of its Privacy Sandbox initiative, such as ways advertisers can measure ad traffic and fight ad fraud without relying on cookies. FLoC isn’t intended to be the only method to replace third-party cookies, but part of a collection of privacy-focused tools for online advertisers.
FLoC-based cohorts will be available for public testing through origin trials in March, and advertisers can begin testing FLoC-based cohorts in Google Ads in the second quarter, Bindra said. The change will also impact browsers based on Google’s Chromium technology such as Microsoft’s Edge browser. Users will see an on-off switch to take part in Privacy Sandbox with the Chrome 90 release in April.