Brave open sources Cookiecrumbler to make cookie consent blocking smarter

Brave just made a move that should make privacy enthusiasts pretty happy. The company has officially open sourced Cookiecrumbler, a tool designed to automatically detect and help block those obnoxious cookie consent banners you see across the Web. These pop-ups are not only annoying but, according to research, often track users even when they click reject. Cookiecrumbler aims to stop that nonsense while avoiding the headaches that can come with sloppy blocking rules.

Lately, Brave has been my go-to web browser. It’s open source, cross-platform, and runs beautifully on Linux, which I appreciate as a Linux fan. Even better, it handles ad-blocking on iOS -- something many other browsers don’t offer. And perhaps most importantly, it does all of this without relying on Google.

Now, blocking cookie notices sounds easy on paper, but it comes with risks. If you block the wrong element on a site, you can break critical features like checkout buttons or navigation menus. Brave has seen plenty of issues where aggressive blocking rules caused scrolling problems or blanked out pages entirely. That’s why the company has been cleaning up community-maintained block lists, stripping out the kinds of generic rules that tend to cause breakage.

This is where Cookiecrumbler comes in. Instead of relying on broad, one-size-fits-all rules, Brave is using large language models to scan websites and automatically identify cookie notices, even when those banners show up in different languages or regions. The tool can also suggest how to block these notices safely, but Brave still keeps human reviewers in the loop to make sure things don’t break. It’s a balance of automation and human judgment.

Brave isn’t just sharing the code for Cookiecrumbler -- it’s also publishing the results of its website crawls to GitHub. This invites the larger ad-blocking community to jump in and help confirm detections, improve rules, and make cookie notice blocking smarter across the board.

The process starts with Brave creating custom lists of popular websites for different regions. From there, automated crawlers visit these sites using proxies that simulate being in various locations. Cookiecrumbler then fires up a headless browser, scans the page for likely cookie banners, and runs those elements through the LLM to confirm whether they’re notices that need blocking. If so, the tool can even suggest a fix.

For now, Cookiecrumbler operates on Brave’s backend, but the company is exploring the idea of eventually bringing this detection system into the browser itself. Of course, any move like that would only happen after a thorough privacy review -- Brave’s entire approach is about respecting user privacy and giving people control.

Brave first showed off Cookiecrumbler under a different name at last year’s Ad Filtering Dev Summit. Since then, it has made steady progress, cutting down on false positives, adding language support, and improving its ability to handle regional variations. Brave says the results have already led to fewer complaints about broken sites and better user retention overall.

By open sourcing Cookiecrumbler and making its findings public, Brave is giving users and developers alike a way to fight back against the frustrating cookie banner problem -- and doing it without breaking the Web in the process.