It has been discovered that Firefox secretly incorporates Brave's ad-blocking technology.
It has been revealed that Mozilla's browser, Firefox 149, incorporates Brave's ad and tracker blocking engine, 'adblock-rust.' This change was not mentioned in the Firefox 149 release notes, and it is not enabled as a standard feature at the time of writing.
Firefox browser has started shipping Brave's adblock-rust engine
Firefox Has Quietly Integrated Brave's Adblock Engine
https://itsfoss.com/news/firefox-ships-brave-adblock-engine/
According to Shivan Kaul Sahib, Vice President of Privacy and Security at Brave, Firefox 149 will include adblock-rust, the open-source Rust engine used in Brave's native content blocker. Sahib commented, 'This is fantastic!'
adblock-rust is the core engine for Brave's ad-blocking functionality. Written in Rust and provided under the MPL-2.0 license, it features network request blocking, cosmetic filtering to hide elements on a page, and support for uBlock Origin-compatible filter list syntax.
This change was implemented through Bug 2013888, which was registered on Mozilla's Bugzilla. It was handled by Mozilla engineer Benjamin VanderSloot, and the bug is titled 'Add a prototype rich content blocking engine.'
However, this doesn't mean that Firefox now has a built-in ad-blocking feature. According to Sahib, this engine is disabled by default and doesn't include a user interface or filter list. In other words, it's not a feature that the average user can easily enable and use from the regular settings screen, and at this stage, it's closer to an experimental implementation.
At least as of the time Sahib pointed out, Mozilla had not announced adblock-rust as an official ad-blocking feature for Firefox, nor was it mentioned in the release notes. Therefore, while the inclusion of a Brave-derived engine in Firefox is interesting, we need to carefully consider whether it indicates future product direction.
On the other hand, Waterfox, an open-source browser derived from Firefox, is said to have adopted adblock-rust based on the Firefox implementation. This shows that the experimental introduction in the main Firefox browser has led to the extension of functionality in the derived browsers as well.
Waterfox becomes the latest browser to embed Brave's adblock-rust engine. Validation++ for Brave's thesis that ad & tracker blocking belongs within the browser (not bolted on top) for better control, better blocking and better performance.
pic.twitter.com/Hor6fNrKJa — Shivan Kaul Sahib (@shivan_kaul) March 30, 2026
According to Sahib, you can try out the adblock-rust implementation by changing the settings in about:config and specifying filter lists for EasyList and EasyPrivacy.
The following shows how ads are blocked when adblock-rust is enabled in Firefox.
However, it is explained that if the existing Enhanced Tracking Protection is running, it is difficult to determine whether the block is due to adblock-rust, so this feature needs to be turned off on the test site. Also, since it is an experimental feature, it is recommended to try it in a test environment rather than using it in normal circumstances.
Sahib stated, 'These days, there are no browsers that don't block third-party ads and trackers by default. For example, Firefox still doesn't block tracking query parameters. It will be very interesting to see how this initiative develops in the future.'
Related Posts:
in Software, Posted by log1i_yk