uBlock Origin Guide: What It Is, Features, and Setup

What it is

uBlock Origin (frequently referred to as uBO) is a free and open-source browser extension designed for content filtering. According to the project README, it is an efficient blocker created for Chromium and Firefox that is engineered to be fast, lean, and frugal with system CPU and memory resources. Rather than operating solely as an ad blocker, the repository describes it as a wide-spectrum content blocker capable of neutralizing a broad range of privacy-invading elements before they load in a web browser.

To clarify the terminology for general users, a content blocker is an extension that inspects web traffic and selectively restricts elements such as visual advertisements, tracking scripts, and remote connections. According to the project documentation, uBlock Origin’s primary mission is to help people neutralize privacy-invading methods that load when visiting modern websites. The project emphasizes that this layer of defense is designed to welcome individuals who prefer not to rely on complex technical methods.

The project also documents an underlying philosophy regarding digital rights. According to its manifesto and README, choosing to block unwanted digital content is not theft; the documentation argues that framing blocking as theft leads to the criminalization of an individual’s right to privacy. The utility was created under the principle of being built for users by users, and the project explicitly avoids commercial monetization, stating that no donations are sought.

What it can do

According to the repository documentation, uBlock Origin blocks a broad variety of unwanted network elements immediately upon installation. By default, it is configured to block advertisements, tracking scripts, cryptocurrency miners, unsolicited popups, annoying anti-blocker notices, and malicious web addresses.

The extension carries out these tasks through the use of filter lists. A filter list is a structured catalog of rules that instructs the blocker which web servers, scripts, or interface components should be restricted or hidden. Out of the box, uBlock Origin enables several established default lists, including EasyList, EasyPrivacy, Peter Lowe’s Blocklist, the Online Malicious URL Blocklist, and uBO’s own built-in filter lists. For context, the project README notes that Adblock Plus installs with only EasyList, ABP filters, and Acceptable Ads enabled by default.

Beyond its pre-activated lists, uBlock Origin provides several capabilities and customization options:

• Customizing Preselected Lists: Users can easily deselect any default filter lists if they consider the blocking behavior too strict, or they can activate additional available lists to broaden protection.
• Support for Hosts Files: The extension can import and process hosts files, which are plain-text records used to restrict connections at the domain level.
• Extended Filter Syntax: Built upon standard EasyList filter syntax, the software extends this syntax to support custom rules, procedural filters, and personalized blocking criteria.
• Dual Operational Modes: The extension provides two distinct ways to interact with its controls:
  1. Basic Mode: A simple popup user interface designed for an install-it-and-forget-it setup. According to the project documentation, this mode is configured optimally right from the start without requiring user configuration.
  2. Advanced Mode: An advanced popup user interface that introduces an interactive, point-and-click firewall. This dynamic filtering system allows users to inspect network traffic on a per-site basis and decide whether to block or allow individual connections, third-party domains, or scripts.

Additionally, the project documentation emphasizes an important best practice: users should not run uBlock Origin alongside any other content blocker. According to the README, uBlock Origin performs as well as or better than most popular blockers, and combining it with other blockers can prevent its privacy features and anti-blocker defusing mechanisms from functioning correctly. For modern extension environments, the project also links to a related companion effort known as uBlock Origin Lite, designed specifically for Manifest Version 3 systems.

How to get started

Setting up uBlock Origin depends on the platform and browser you choose. The project documentation outlines availability, status, and installation methods across several environments:

• Firefox: The extension is available through the official Firefox Add-ons repository for both desktop and Android editions, alongside separate development builds. According to the project README, uBlock Origin works best on Firefox.
• Chromium-Based Browsers: The extension is compatible with Chromium-based browsers generally, though store availability varies by browser vendor:
  • Microsoft Edge: Available through Microsoft Edge Add-ons. According to the project README, the extension was published by Nicole Rolls until version 1.62, followed by an ownership transfer at version 1.64. The documentation references Microsoft’s transition schedule moving consumer extensions from Manifest Version 2 (MV2) to Manifest Version 3 (MV3) starting in August 2026 through the end of 2026, with enterprise deprecation following in early 2027.
  • Opera: Available via the Opera Add-ons catalog.
  • Chromium and Chrome: The project README notes that the extension was removed from the Chrome Web Store on August 31, 2026, corresponding to the timeline phasing out Manifest Version 2 extensions.
• Thunderbird: Available through Thunderbird Add-ons. The project documentation notes that in Thunderbird, uBlock Origin does not modify or filter emails, but instead operates exclusively on RSS and web feeds. The documentation also states that the add-on in the Thunderbird store is stuck at version 1.49.2 and no longer updated there, meaning subsequent releases must be installed from GitHub.
• Manual Installation via GitHub: Pre-built packages for Firefox, Chromium MV2, and Thunderbird are published under GitHub Releases. When installing manually from GitHub, the documentation notes that Chromium and Thunderbird installations generally will not receive automated updates.
• Enterprise Deployment: Organizations managing fleets of computers can consult the project wiki for technical procedures covering automated deployment in corporate environments.

Once installed, the extension runs automatically in Basic Mode. Users who wish to customize their setup can open the settings dashboard to adjust filter lists, or activate Advanced Mode to access the dynamic filtering firewall. For documentation and assistance, users can consult the project Wiki, seek help within the /r/uBlockOrigin community on Reddit, or contribute translations through the Crowdin platform.

Pricing and requirements

Pricing and plans are subject to the official project page. According to repository metadata, uBlock Origin is distributed as free, open-source software under the GNU General Public License v3.0 (GPL-3.0). As stated in the project documentation, it is developed for users by users and does not solicit monetary donations. The author notes that individuals interested in contributing should instead consider supporting the maintainers who create and update the public filter lists that content blockers rely on.

In terms of technical requirements, the extension requires a supported browser environment, such as Firefox (desktop or Android), an MV2-compatible Chromium browser (such as Microsoft Edge or Opera), or Thunderbird for web feed handling. Because it is built as a Manifest Version 2 extension, ongoing availability is governed by individual browser deprecation timelines. According to the project README, uBlock Origin is designed to be fast and lean, remaining efficient in its use of memory and CPU cycles during active web browsing. Standard extension permissions are required upon installation so the tool can monitor network requests and apply blocking rules across visited pages.

Who it is for

Based on the capabilities and modes described in the project repository, uBlock Origin is suited for several types of users:

• General Web Users: People seeking an easy, install-it-and-forget-it content blocker that automatically eliminates ads, trackers, and malicious domains without requiring manual configuration.
• Privacy-Minded Individuals: Users who wish to defend against invasive browser tracking, coin miners, and unwanted network connections under a transparent, open-source license.
• Power Users and Technical Enthusiasts: Individuals who want granular control over their network traffic through per-site firewall rules, dynamic filtering, custom syntax, and external hosts files.
• Mobile and Feed Users: People using Firefox on Android who want content blocking on mobile devices, as well as Thunderbird users who wish to filter web feeds.
• Enterprise Administrators: Network administrators looking to roll out an efficient content blocker across organization-managed workstations.

Alternatives

The AdGuard Browser Extension is an open-source browser extension option available on GitHub.

The Privacy Badger extension is another browser-based privacy tool hosted on GitHub.

Sources

• https://github.com/gorhill/uBlock
• https://github.com/AdguardTeam/AdguardBrowserExtension
• https://github.com/EFForg/privacybadger