{"id":5833,"date":"2026-04-24T04:12:27","date_gmt":"2026-04-24T11:12:27","guid":{"rendered":"https:\/\/catbradley.io\/?p=5833"},"modified":"2026-04-24T04:12:27","modified_gmt":"2026-04-24T11:12:27","slug":"firefox-has-quietly-integrated-braves-adblock-engine","status":"publish","type":"post","link":"https:\/\/catbradley.io\/?p=5833","title":{"rendered":"Firefox Has Quietly Integrated Brave's Adblock Engine"},"content":{"rendered":"

Back in March, Firefox 149<\/a> was released with many changes, like a free built-in VPN, a Split View<\/em> that allows the loading of two pages side by side, and the XDG portal file picker as the new default on Linux.<\/p>\n

However, an interesting addition had gone mostly unnoticed until now.<\/p>\n

Firefox has Some Brave in it now<\/h2>\n
\"this<\/figure>\n

Shivan Kaul Sahib<\/a>, the VP of Privacy and Security at Brave<\/a>, has put out a blog post<\/a> about something that didn’t make it into the Firefox 149 release notes at all. The browser now ships adblock-rust<\/a>, Brave’s open source Rust-based ad and tracker blocking engine<\/strong>.<\/p>\n

The change landed via Bugzilla Bug 2013888<\/a>, which was filed and handled by Mozilla engineer Benjamin VanderSloot<\/a>. The bug is titled “Add a prototype rich content blocking engine,<\/em>” and keeps the engine disabled by default with no user interface or filter lists included.<\/p>\n

For informational purposes, adblock-rust<\/a> is the engine behind Brave’s native content blocker (aka ad blocker<\/em>). It is written in Rust<\/strong> and licensed under MPL-2.0<\/strong>, handling network request blocking, cosmetic filtering, and features a uBlock Origin<\/a>-compatible filter list syntax.<\/p>\n

Shivan also mentions that Waterfox<\/a>, the popular Firefox fork, has adopted adblock-rust<\/a>, building directly upon Firefox’s own implementation.<\/p>\n

Want to test it?<\/h2>\n

Before starting, head to Enhanced Tracking Protection<\/a>‘s shield icon in the address bar and turn it off for the website you will be testing this with. This way, adblock-rust is doing the work, not Firefox’s existing feature.<\/p>\n

\n
\ud83d\udea7<\/div>\n
I suggest testing this experimental feature on a throwaway installation of Firefox.<\/div>\n<\/div>\n

Now open a new tab and go to about:config<\/code>. Accept the warning when it shows up. Search for privacy.trackingprotection.content.protection.enabled<\/code> and set it to “true<\/em><\/strong>” by clicking on the toggle. \ud83d\udc47<\/p>\n

\n
\n
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\"firefox<\/div>\n
\"\"<\/div>\n
\"\"<\/div>\n<\/div>\n<\/div>\n<\/figure>\n

Next, search for privacy.trackingprotection.content.protection.test_list_urls<\/code>, click on the “Edit” button, and paste the following value to add the EasyList<\/a> and EasyPrivacy<\/a> filter lists to Firefox:<\/p>\n

https:\/\/easylist.to\/easylist\/easylist.txt|https:\/\/easylist.to\/easylist\/easyprivacy.txt<\/code><\/p>\n

Remember to click on the blue-colored “Save<\/em>” button before moving on.<\/p>\n

\n
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\"\"<\/div>\n
\"\"<\/div>\n<\/div>\n<\/div>
\n

Left: advertisement shown; Right: advertisement blocked<\/em><\/i><\/p>\n<\/figcaption><\/figure>\n

Now visit a site with known ads, like Yahoo<\/a> (as I did above<\/em>). If it’s working, ad slots will still render in the page layout, but the actual ad content will be blocked. In my test, the banner on Yahoo came up showing only the text “Advertisement<\/em>” with the advert bit stripped out.<\/p>\n

<\/p>\n

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