uBlock Origin (uBO)

About uBlock Origin (uBO)

uBlock Origin is an open-source content blocker for Firefox and Chromium-based browsers. By default it blocks ads, trackers, coin miners, popups, anti-blocker scripts, and known malware sites, using EasyList, EasyPrivacy, Peter Lowe's Blocklist, the Online Malicious URL Blocklist, and uBO's own filter lists. The project describes its goal as helping users neutralize privacy-invading methods on websites. This is a stated goal, not a guarantee of privacy or safety.

The extension is available in a simple Basic Mode and an Advanced Mode, which adds a per-site point-and-click firewall. Users can turn off preselected filter lists, and the tool supports hosts files and custom rules. Firefox is the browser the project says it works best on, and a Firefox version is available for desktop and Android. Availability for Chromium is changing: the Chrome Web Store listing was removed on 2026-08-31 according to the source, and Chromium versions must be installed manually from GitHub releases and usually do not update automatically. The Thunderbird version is no longer updated and remains at 1.49.2. The project advises against running uBO alongside any other content blocker.

Key features

• Blocks ads, trackers, coin miners, popups, and anti-blocker scripts by default
• Blocks known malware sites using built-in malicious URL blocklists
• Supports hosts files and EasyList filter syntax with custom rules
• Basic Mode for set-and-forget use and Advanced Mode for control
• Advanced Mode includes a per-site point-and-click firewall
• Lets users deselect any preselected filter lists

uBlock Origin (uBO) at a glance