Use the DuckDuckGo Extension to Block FLoC, Google’s New Tracking Method in Chrome

Filed under DuckDuckGo News on
  • Google has created a new tracking method called FLoC, put it in Chrome, and automatically turned it on for millions of users.
  • FLoC is bad for privacy: It puts you in a group based on your browsing history, and any website can get that group FLoC ID to target and fingerprint you.
  • You can use the DuckDuckGo Chrome extension to block FLoC's tracking, which is an enhancement to its tracker blocking and directly in line with the extension's single purpose of protecting your privacy holistically as you use Chrome.
  • DuckDuckGo Search (via our website duckduckgo.com) is now also configured to opt-out of FLoC, regardless if you use our extension or app.

What just happened?

If you're a Google Chrome user, you might be surprised to learn that you could have been entered automatically into Google's new tracking method called Federated Learning of Cohorts (FLoC). It groups you based on your interests and demographics, derived from your browsing history, to enable creepy advertising and other content targeting without third-party cookies. After a short trial period, Google decided not to make this new tracking method a user choice and instead started automatically including millions in the scheme. If you're reading this in Chrome while logged in to a Google account, yes, that likely means you too, and if not now, then eventually.

As a user, what can I do to avoid this?

The criteria for being opted into FLoC are somewhat hidden and conflicting, but there are three methods for blocking FLoC:

  1. Don't use Google Chrome! Right now FLoC is only in Google Chrome, and no other browser vendor has expressed an intention or even interest to implement it. There are various browsers that are free to download, and we recommend some in our guide to Google alternatives. On iOS or Android we suggest you use our own mobile browser, which offers best-in-class privacy protection by default when searching and browsing.
  2. Install the DuckDuckGo Chrome extension. In response to Google automatically turning on FLoC, we've enhanced the tracker blocking in our Chrome extension to also block FLoC interactions on websites. This is directly in line with the single purpose of our extension of protecting your privacy holistically as you use your browser. It’s privacy, simplified. (If you use a non-Chrome browser, you can get our extension here.) The FLoC blocking feature is included in version 2021.4.8 and newer of the DuckDuckGo extension, which should auto-update, though you can also check the version you have installed from the extensions list within Chrome.
  3. Change your Chrome and/or Google settings, which we recommend you do in any case if you continue to use Chrome. It seems (but Google isn't very clear about this so we aren't certain) that if you perform any of the following, then Google will exclude you from FLoC, at least for the time being. And as there are still many unknowns and things are changing rapidly, the effectiveness of these steps may change in future.

Note that even if you change these settings, we also recommend installing the DuckDuckGo Chrome extension to get holistic privacy protection when using Chrome, including private search, tracker blocking, Smarter Encryption, and Global Privacy Control. For non-Chrome desktop browsers, you can get our extension here.

So, what is FLoC anyway?

With browsers dropping support for third-party cookies, FLoC is Google's approach for replacing them. It's being developed in the open and is claimed by Google to be good for privacy. However, it has received widespread criticism from privacy experts, including from EFF who say it's a "terrible idea" and implored Google "please don't do this." We agree with their assessment, and, in a world where it does exist, it should be explicitly opt-in for users (free of dark patterns). In addition, while Google isn’t phasing out third-party cookies in Chrome until at least 2023, FLoC is already live today in 2021.

What are some of those privacy concerns with FLoC?

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.

Google itself maintains detailed profiles of users, built up over time from what they've learned about users (including through passive trackers lurking on most websites), but with FLoC they're now exposing your derived interests and demographics from this profile to the websites you visit via FLoC IDs. Although the cohorts you belong to over time are non-descriptive and represented by an anonymous-looking number, it won't be long before people or organizations work out what FLoC IDs really mean, e.g. what interests and demographic information they are likely correlated with.

But don't just take it from us. Google itself has said this new approach is at least 95% as effective as third-party cookie tracking, continuing the ability to target people based on age, gender, ethnicity, income, and many other factors. This targeting, regardless of how it's done, enables manipulation, discrimination, and filter bubbles that many people would like to avoid.

Please also note that FLoC IDs will also be accessible by third-party trackers lurking on websites. As we’ve explained recently, to protect yourself from these trackers, you need to stop them from loading in your browser, which is also accomplished by the DuckDuckGo extension and app.

As a website owner, what can I do to avoid this?

Websites can take steps to protect the privacy of their users by opting out of FLoC, which would be applicable to all their visitors. It's done by simply sending the following Permissions-Policy HTTP response header:

Permissions-Policy: interest-cohort=()

Some publishers like The Markup and The Guardian have already done so, as have we at DuckDuckGo Search, and we encourage others to follow.

What’s next?

We're disappointed that, despite the many publicly voiced concerns with FLoC that have not yet been addressed, Google is already forcing FLoC upon users without explicitly asking them to opt in. We're nevertheless committed and will continue to do our part to deliver on our vision of raising the standard of trust online.


For more privacy advice follow us on Twitter, and stay protected and informed with our privacy newsletters.

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Use the DuckDuckGo Extension to Block FLoC, Google’s New Tracking Method in Chrome
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