Google’s proposed alternative to third-party cookies has been panned by Chromium developers and privacy advocates.

The tech giant started testing its new tracking mechanism, the Federated Learning of Cohorts (FLoC), last month but is meeting resistance from developers of other browsers who have so far said they will not support the new system.

FLoC is proposed as an alternative to invasive third-party cookies and fingerprinting trackers that follow your activity around the internet in order to deliver targeted advertising.

Google said it will soon remove third-party cookies from Chrome in favour of “privacy-preserving APIs” like FLoC which essentially tracks a user’s browsing activity locally, analyses the data, and creates a cohort ID to give to advertisers who will know broad features about the user and their interests, but won’t be able to identify them individually.

The Electronic Frontiers Foundation (EFF) quickly came out against FLoC, said the technology is sold as a “false premise that we have to choose between ‘old tracking’ and ‘new tracking”.

“It’s not either-or,” said the EFF. “Instead of re-inventing the tracking wheel, we should imagine a better world without the myriad problems of targeted ads.”

FLoC features have already been shipped to other browsers built on Google’s open source Chromium project such as Firefox, Brave, and Microsoft Edge.

Microsoft appears to have disabled FLoC in Edge, according to Bleeping Computer, but has only offered a vague statement about its intentions when it comes to cookie alternatives.

“The industry is on a journey and there will be browser-based proposals that do not need individual user IDs and ID-based proposals that are based on consent and first party relationships,” Microsoft said.

“We will continue to explore these approaches with the community.”

Mozilla, on the other hand, has been more direct saying it has “no current plans” to implement FLoC in its popular Firefox browser.

“We don’t buy into the assumption that the industry needs billions of data points about people, that are collected and shared without their understanding, to serve relevant advertising,” Mozilla said.

“Advertising and privacy can co-exist. And the advertising industry can operate differently than it has in past years.”

Privacy-focused Chromium browser Brave condemned FLoC in a lengthy blog post tearing down assumptions around how the proposed technology would preserve privacy.

“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 prioritise maintaining the structure of the Web advertising ecosystem as Google sees it,” Brave said.

“For the Web to be trusted and to flourish, we hold that much more is needed than the complex yet conservative chair-shuffling embodied by FLoC and Privacy Sandbox.”

In response to the Brave blog post, Apple Safari engineer John Wilander said the company was still undecided about whether it would adopt Google’s tracking standard.

You can check to see if your Chrome browser has been selected for FLoC testing through this website created by EFF.