ublock

uBlock Origin (uBO) is a wide-spectrum content blocker for Chromium and Firefox, designed to be CPU and memory-efficient. It blocks ads, trackers, coin miners, popups, annoying anti-blockers, and malware sites by default. It ships with filter lists such as EasyList, EasyPrivacy, Peter Lowe's Blocklist, Online Malicious URL Blocklist, and uBO's own filters, and supports additional lists and hosts files. It uses the EasyList filter syntax and extends it with custom rules and filters. The extension offers two usage modes: a basic popup interface for install-and-forget use, and an advanced mode with a point-and-click per-site firewall using dynamic filtering. The wiki contains documentation for both, and support discussions happen on the uBlockOrigin subreddit. Installation options include Firefox Add-ons, Microsoft Edge Add-ons, Opera Add-ons, Thunderbird Add-ons, and manual installation from GitHub Releases. The Thunderbird version is no longer updated and is stuck at 1.49.2, with later versions requiring GitHub Releases. The Chrome Web Store listing was removed on 2026-08-31 due to Manifest V2 deprecation; Edge's consumer MV2 transition begins in August 2026. The Chromium and Thunderbird versions usually will not auto-update when installed manually. The project recommends not using uBO alongside other content blockers, as other blockers can prevent uBO's privacy and anti-blocker-defusing features from working correctly. Translations are managed on Crowdin. The project is free and open-source under GPLv3, with no donations sought. A related MV3-based project is uBlock Origin Lite.