"An LLM analyses each site's content to detect unblocked cookie consent notices and suggests ways to block them."
Brave, a privacy-centric browser, recorded 84.8 million monthly active users as of March 2025. While it may not replace Google Chrome for most users, it has garnered a loyal following among privacy enthusiasts, who swear by it.
The web browser is known to incorporate privacy-preserving features for users, including the blocking of trackers and advertisements on the web. They also incorporate AI features in several forms.
Recently, the company open sourced Cookiecrumbler, a tool that detects cookie consent notices on websites using open source LLMs and recommends fixes for them.
How does it work? Why does it focus on cookie consent notices? Can users download it as an extension?
In a blog post, Brave stated, "Brave blocks cookie consent notices by default. These banners are both annoying and harmful to user privacy (given how websites often implement them)."
It explained that blocking cookie consent notices offers benefits in terms of privacy and reduces annoyances, but it does include some risks. With the current blocking mechanisms, website functionalities can break, resulting in irregular layouts and disrupted checkout flows, which prevent users from using the website as expected.
The company has encountered various issues when a cookie consent notice block is applied without taking into account any special considerations. A generic rule-based system, such as an adblock list, does not prevent it either.
Hence, they have been trying to improve the cookie consent notice blocking lists to avoid such issues.
To enhance the user experience while ensuring that cookie notices are blocked, Brave introduced a tool that utilises open source LLMs to automate the process of detecting cookie notices.
The tool has now been open sourced, after several months of running on the server side for fine-tuning and optimisation.
Cookiecrumbler automates the detection of various site-specific variations, including non-English cookie notices. The company explains that using large language models (LLMs) for this task is easy, considering cookie consent notices often feature similar, repetitive text. These notices are considered low-risk -- human reviewers can remove false positives upon visual inspection -- and cost-effective to process via LLMs.
With the help of an LLM, human reviewers will be able to focus on meaningful work, such as refining the filter list and coordinating with community members to help confirm and refine Cookiecrumbler.
Explaining how it works, Shivan Kaul Sahib, VP of privacy and security at Brave Software, told AIM, "On Brave's backend servers, we automatically visit popular regional websites (US, UK, EU, etc.) using an instrumented version of Brave. An LLM analyses each site's content to detect unblocked cookie consent notices and suggests ways to block them."
"We then share these results with the adblocking community to collectively address cookie notices."
Sahib mentioned that they have experimented with various AI models and are currently using Llama 3 8B on AWS Bedrock.
He pointed out that a user does not need to take any action to use this feature. "All Brave users (including users in India via EasyList Cookie list) automatically get the benefits of less breakage and more cookie notice blocking."
Sahib further clarified that the tool runs completely on the backend and no user data is ever used.
While the company does not plan to release it as an extension, a Brave team member revealed in a Reddit thread that they may roll out a client-side version in the future. However, this will only happen after a thorough privacy review, ensuring that it protects user privacy.
The tool also supports different locations and languages, which should help tackle a range of cookie notices globally.
The company, with the help of the tool, adds the list of websites where the cookie notice was detected to its GitHub repository.
With such a tool, Brave aims to enhance the user experience and privacy by reducing site breakage issues by blocking cookie notices. Will other web browsers follow this? Only time will tell.
