Firefox 149 silently shipped Brave’s adblock-rust engine disabled by default; this extension adds a UI to activate and configure it.
Key Takeaways
Firefox 149 (March 2026) bundled adblock-rust with no release notes, no UI, and no default activation – controlled only by two about:config prefs.
adblock-rust supports network request blocking, cosmetic filtering, and full uBlock Origin filter list syntax compatibility.
Standard MV3 WebExtensions cannot write arbitrary about:config prefs; the extension handles the ETP toggle via browser.privacy API and guides manual one-time setup for the two adblock-rust prefs.
An earlier version used Firefox’s experiment_apis mechanism but that path only works on Nightly and Developer Edition, not Release Firefox.
Ships with 8 preset filter lists (EasyList, EasyPrivacy, Fanboy Cookie Monster, uBO Annoyances, AdGuard, etc.) and builds the required pipe-separated pref value automatically.
Hacker News Comment Review
Commenters are skeptical of the practical gain: the key open question is whether adblock-rust offers any concrete blocking improvement over ETP plus uBlock Origin, which the README does not directly answer.
A philosophical objection surfaced: browser-native blocking puts control in Mozilla’s hands, where institutional incentives around the ad industry may conflict with user interests – commenters prefer blocking to remain a user-controlled extension layer.
Notable Comments
@kgwxd: “Tracker/Ad blocking should forever be an extension, maintained by someone with zero obligation to, or association with, the ad/tracking industry.”
