Update 1 (04/19/2021 @ 1:15 PM ET): Another major blow has been dealt to Google's proposed alternative to third-party cookies, FLoC. Click here for more information. The article, as published on April 13, 2021, is preserved below.

Google recently began testing an “origin trial” in Chrome with a new piece of web technology called Federated Learning of Cohorts (FLoC), which is replacing third-party cookies. In response, DuckDuckGo, Brave, and Vivaldi have all announced that they will disable Google’s FLoC, calling it a “step in the wrong direction.”

Basically, Google’s FLoC replaces third-party cookies by grouping Chrome users based on their interests and demographics. Google claims it’s a better alternative to third-party cookies, but privacy advocates disagree — and so does DuckDuckGo, Brave, and Vivaldi. The disagreement appears to focus on the fact that Google isn’t getting consent before tracking users.

All three have published blog posts openly pushing back against FLoC, with DuckDuckGo releasing a Chrome extension that will block FLoC’s tracking. DuckDuckGo explains some of the privacy concerns over FLoC on its blog:

With FLoC, by simply browsing the web, you are automatically placed into a group based on your browsing history (“cohort”). Websites you visit will immediately be able to access this group FLoC ID and use it to target ads or content at you. It's like walking into a store where they already know all about you! In addition, while FLoC is purported to be more private because it is a group, combined with your IP address (which also gets automatically sent to websites) you can continue to be tracked easily as an individual.

Brave, meanwhile, said it vehemently opposes FLoC, and any feature that’s designed to share information about users and their interest without first getting consent. Brave said in response to Google’s practices, it has removed FLoC in the Nightly version of both Brave for desktop and Android.

Brave voiced its displeasure with Google’s methods:

It is disappointing to see Google, instead of taking the present opportunity to help design and build a user-first, privacy-first Web, proposing and immediately shipping in Chrome a set of smaller, ad-tech-conserving changes, which explicitly prioritize maintaining the structure of the Web advertising ecosystem as Google sees it.

Vivaldi has also said it won’t support Google’s FLoC, calling its new data harvesting venture “nasty” and saying it “harms user privacy.” The browser maker said it won’t support FLoC because it’s simply a privacy-first feature in disguise.

“Google will continue to build profiles, and track users, in the absence of third-party cookies and localStorage,” Vivaldi said in a blog post. “It presents FLoC as part of a set of so-called ‘privacy’ technology, but let’s remove the pretense here; FLoC is a privacy-invasive tracking technology.”

Privacy advocates argue that FLoC will actually expose your data more than ever, not protect it, with Vivaldi claiming FLoC has “serious implications on a society as a whole.

If you’re concerned about Google’s FLoC, the easiest thing is to avoid Chrome altogether. You can use Brave or Vivaldi instead, or you can use DuckDuckGo’s Chrome extension or DuckDuckGo Search, which has been configured to opt-out of FLoC.


Update 1: Big companies are hesitant to support FLoC

It was unsurprising to hear Brave, DuckDuckGo, and Vivaldi come out against Federated Learning of Cohorts (FLoC), Google's proposed alternative to browser cookies. However, Google's new ad technology proposal has been dealt a major blow as it is seeing little support from major browser vendors. As reported by The Verge, Opera, Microsoft, Mozilla, and Apple have yet to publicly agree on the technology. Opera told the publication that it has "no current plans" to enable the feature in its browser and that "it's too early to say" what direction the market will take. Microsoft's statement doesn't explicitly mention Google's proposed technology but rather states that they're open to exploring various approaches with the community. Mozilla also offered a non-committal response, while a WebKit engineer at Apple hinted at the company's thinking on Twitter.

Most of the major players are taking a softer stance towards FLoC than the smaller, more privacy-focused companies. They may very well eventually agree to it, but for now, they all seem to want to see the W3C's web standards process play out rather than watch Google railroad the feature onto the web using its browser and browser engine dominance. The matter is being taken seriously enough to warrant a proposal in WordPress Core to "treat FLoC like a security concern," potentially blocking the feature on websites using the popular content management system. With the number of companies taking a stance directly against or not-in-favor of FLoC, Google has a lot of work to do if it wants its proposed third-party cookie alternative to be adopted by the open web.