Call for volunteers in a user study -- Study is now over

EDIT: Study is now over. Thank you all for the help.
EDIT: Now also compatible with Brave Release versions.

Brave is participating in a User Study organized by the University of Cambridge, aiming to enable privacy-preserving Federated Learning in serving advertisements in a real setting.

We are looking for 500 Brave users of Desktop release (i.e., Windows, macOS, or Linux) for a user study that will enable us to improve our local machine learning models around Brave Ads. You can take part if you are 18 years of age or older, and live in any of the Brave Ads Supported Countries.

We will be looking to respectfully collect low-sensitivity user behavioral data, such as the number of tabs you have open (but not the actual URLs or the page content), what time of the day you clicked on an ad (but not what ad), and how long you waited before dismissing an ad. No personal data or data about your browsing history will be recorded for this user study.

You have complete control and can opt-out at any moment. Your data will be collected locally for 28 days. During this time, you can inspect the data and see what exactly has been collected at any point. You will receive instructions about how to do so. If you’re happy with it, you can then choose to submit it to us for research purposes. The data is only on your device until you choose to send it to us. You can also have a look at the project’s source code on GitHub.

At the end of the study, you can enter our prize raffle for the chance to win one of the twenty (20) $50 Amazon gift vouchers. There’s also a cool POAP (Proof of Attendance Protocol) NFT (non-fungible token) up for grabs!

More information about the study and how you can participate can be found here.

Feel free to contact me with any questions.


Awesome, I’m passing word along in a few places.

@minoskt, just to verify, you’re saying only can be done if using Nightly or Beta version?

Thank you Saoiray. Only in Nightly and Beta for now, will be available to Brave Release very soon (i.e., in a week or so).

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Just a little feedback. Had someone respond on a Reddit post I made and they were getting a blank page when “trying to sign up.” I checked out and noticed that the link that says Sign up here with your email address for our mailing-list is actually a mailto link. When I clicked it initially, it opened to a blank page as well, but I at least had the prompt below appear:

Private Ads with Brave and Flower_ Call for volunteers in federated learning user study. _ CaMLSys - Brave 8_26_2022 9_26_13 PM

So I’m guessing some didn’t get that notice. Might want to think of a different method or just provide the email address directly, if people are supposed to be sending emails. Unless that’s part of the screening process, lol.

Thank you for the useful feedback. The instructions are now updated and are more clear regarding the enrolment to the mailing list.

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Now also compatible with Brave Release versions.


Hi, I enabled Brave Nightly to participate as a volunteer and I subscribed to the list, at first I received an email welcoming the subscription, but I have not received more information, I enabled it on August 29. Can I now send the collected data?


Thanks for helping us out. Please expect an email soon with further instructions.



OK. Excuse me, Does it affect anything if I delete the browsing history, with the data that it has been collecting?

Not at all. We do not touch / collect anything about your browsing history anyway.

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@minoskt I forget, is it supposed to email us again when it’s time? I ended up signing up for it here on my Desktop once it was able to run on Release version. Quite frankly, I kind of forget when I activated it. Definitely going to have to dig through emails to see what it said when I signed up for it, hoping I didn’t accidentally delete it, lol.

Hi, I would like to participate, but I am likely to change my laptop in a few weeks. Would this be an obstacle to this, given the data to be collected?

Hello. University of Cambridge maintains the mailing list. I just contacted them and they should sent an email with further instructions by tomorrow.

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Unfortunately it is since all data are being collected locally. As long as you can keep using the laptop as your main machine for four weeks you should be fine.

Alternatively, you can extract the data from both machines (email with instructions will arrive tomorrow), and join them manually. Happy to help with that if you want.


So can I send data from my two browsers from one registered email? I would like to know the process then.

Indeed. The data submission will take place using a survey type of portal. The data are extracted into a csv file. You can extract data from both machines, merge them (i.e., append the content of the 2nd file), and submit a single csv file.

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Hello, here again when saving the file with .csv it is saved with Microsoft excel.csv, no problem?
Screenshot 2022-09-29 194951

That’s normal. Your machine has associated csv files with MS Excel, that’s all :slight_smile:

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The article states…

Please don’t hesitate to reach out on the #brave-user-study Slack channel if you have any questions.

…but when I try to access the Channel I’m informed I’m not in that Workspace.

I don’t see an invitation link anywhere to join the Workspace. Am I missing something?


There is a link that you can use to register for the Flower Slack ( You will be then able to join #brave-user-study channel.

Let me know if that works for you.