gorhill/uBlock

What it does

uBlock Origin (uBO) is a wide-spectrum content blocker for Firefox, Chromium-based browsers, and Thunderbird. It filters ads, trackers, coin miners, popups, anti-adblock scripts, and known malware sites by default using filter lists such as EasyList, EasyPrivacy, Peter Lowe's list, the Online Malicious URL Blocklist, and uBO's own lists. It supports hosts files and the EasyList syntax with extensions for custom rules.

The blocker targets users who want defaults that work without tuning, as well as users who want per-site control. The basic popup provides an install-and-forget workflow, while the advanced popup exposes a point-and-click firewall for per-site request filtering. The project says it is designed to be CPU- and memory-efficient.

Quick start

For Firefox desktop or Android, install uBO from Firefox Add-ons. After installation, the default filter lists are preselected; open the extension popup to confirm the protection state and to unselect any list that blocks more than you want.

For per-site control, open the advanced popup and use the firewall matrix to allow or block requests by site and type. The basic popup guide and dynamic filtering guide document the interface. On Chromium, installation is through Microsoft Edge Add-ons or Opera Add-ons; the Chrome Web Store listing was removed on 2026-08-31 due to Manifest V2 deprecation. Development builds and manually installed packages are available from GitHub Releases; note that manually installed Chromium and Thunderbird builds usually do not auto-update.

Constraints

uBO is not meant to run alongside another content blocker, because other blockers can prevent its privacy and anti-adblock-defusing features from working correctly. On Chrome, the full Manifest V2 extension is no longer distributed through the Chrome Web Store; the related uBlock Origin Lite is a separate Manifest V3 project. The Thunderbird add-on is stuck at version 1.49.2, and later versions require GitHub Releases. The extension is licensed under GPL-3.0, and its required permissions are documented separately.

HotRepo's take

The Hacker News threads around this project have consistently focused on practical filtering behavior rather than novelty: the 2021 thread "uBlock Origin works best on Firefox" drew 1,595 points and 509 comments, and release threads for versions 1.20, 1.41, and 1.50 each drew hundreds of points. A commenter in the 1.50 release thread described using uBO to filter out YouTube recommendations and comments, keeping only search and the video (comment), which illustrates the per-site filtering use case beyond ad removal. Another commenter warned that the unrelated ublock.org site is not the same project (comment). These discussions are user opinions from their dates and do not establish current performance or compatibility.