uBlock Origin
uBlock Origin is a free, open-source, cross-platform browser extension for content filtering and ad blocking. It uses filter lists to block ads, trackers, and malware domains while prioritizing CPU and memory efficiency over competing ad blockers.
Score generated by AI agents based on publicly cited evidence and reviewed by the project maintainer. Not independently validated.
Score History
Timeline events are AI-curated from public reporting. Score trajectory is derived from documented events.
Raymond Hill released uBlock as a free, open-source Chrome and Opera extension, forked from his HTTP Switchboard proof of concept. The project had zero monetization, full transparency under GPLv3, and no governance complexity beyond a single volunteer maintainer. The only structural concern was the single-maintainer bus factor risk inherent to a one-person project.
uBlock Origin expanded to Firefox, Edge, and Safari, completed the WebExtensions migration, and experienced 833% user growth driven by rejection of Adblock Plus's paid whitelisting model. The fork from Aljoudi's uBlock was finalized in October 2017. As the extension matured with dynamic filtering, procedural cosmetic filters, and CNAME uncloaking, configuration complexity introduced minimal switching friction for advanced users. Google's 2018 Manifest V3 proposal signaled future platform threats, but the full extension continued to improve, becoming Firefox's most popular add-on by 2022.
Google permanently disabled uBlock Origin on Chrome in July 2025, removing access for 29+ million Chrome users. The YouTube anti-adblock campaign strained volunteer maintainers, and Mozilla's hostile review process led Hill to pull uBlock Origin Lite from the Firefox store. Despite losing its largest platform, the full extension remains available on Firefox and Brave, and the project's zero-monetization, fully-transparent model remains intact.
Alternatives
Free tracker blocker from the EFF that uses algorithmic detection rather than static filter lists. More narrowly focused on trackers than ads, making it a complement rather than a full replacement. Easy to install with zero configuration.
Commercial ad blocker with a free browser extension that scores 100/100 on ad-block tests. Unlike uBlock Origin, AdGuard offers system-wide blocking on desktop and mobile via paid apps. A solid choice if you need blocking beyond just the browser, or if you're stuck on Chrome after Manifest V3.
Dimensional Breakdown
Summaries below were written by AI agents based on the cited evidence. They are editorial interpretations, not independent research findings.
Dimension History
Timeline (41 events)
Raymond Hill Releases HTTP Switchboard Precursor Extension
Raymond Hill (gorhill) released HTTP Switchboard, an experimental Chrome extension giving users granular control over browser requests. The extension served as a proof of concept for content blocking techniques that would later form the foundation of both uMatrix and uBlock Origin.
uBlock First Released on Chrome and Opera
Raymond Hill released uBlock as a free, open-source ad blocker for Chrome and Opera, forked from the HTTP Switchboard codebase. The extension was designed to use community-maintained filter lists (EasyList, EasyPrivacy) while prioritizing CPU and memory efficiency over competing blockers like Adblock Plus.
uMatrix Released as Companion Advanced Filtering Tool
Raymond Hill released uMatrix, a companion extension to uBlock providing fine-grained per-domain control over cookies, scripts, images, and other request types. The tool was designed for advanced users seeking deeper control than uBlock's filter-list-based approach, and shared the same HTTP Switchboard heritage.
Hill Transfers uBlock to Chris Aljoudi Due to Project Fatigue
Raymond Hill transferred the uBlock project to Chris Aljoudi, citing frustration with the increasing demands of user requests. Hill stated the project had 'stopped being a hobby when it felt more and more like a tedious job.' This handoff would prove contentious when Aljoudi launched ublock.org to solicit donations.
Raymond Hill Forks Project as uBlock Origin
Three days after transferring uBlock to Aljoudi, Raymond Hill created a new fork named uBlock Origin. Hill's decision was driven by concerns that the original project would be monetized or altered against his principles. The fork preserved the zero-monetization, zero-donation ethos that defined the project.
Apple Introduces Safari Content Blocker API at WWDC 2015
Apple announced a new content blocker framework for Safari at WWDC 2015, replacing the legacy extension API with a more restrictive declarative model. While framed as a performance improvement, the new API limited ad blocker capabilities compared to Chrome and Firefox extensions, foreshadowing uBlock Origin's eventual loss of Safari support.
Aljoudi Abandons uBlock Development While Continuing Donations
Chris Aljoudi announced that uBlock was no longer under active development, with the last source code committed in August 2015. However, ublock.org continued soliciting donations, prompting Hill to publicly state that 'the donations sought by ublock.org are not benefiting any of those who contributed most to create uBlock Origin.'
uBlock Origin Safari Port Released by Community Contributor
Developer Ellis Tsung (el1t) released an unofficial port of uBlock Origin for Safari, extending the blocker's reach to Apple's browser. The port was maintained separately from the main project and received regular updates synced from the upstream codebase through 2018.
Industry Survey Reports 833% Growth Rate for uBlock Origin
A Comsource and Sourcepoint industry research survey reported that uBlock Origin experienced 833% growth over a 10-month period ending in August 2016, the most rapid growth among any industry software publicly listed at the time. The surge was attributed to user demand for ad blockers that operated outside the 'acceptable advertising' program used by Adblock Plus.
uBlock Origin Released for Microsoft Edge by Community Developer
Developer Nik Rolls released a fork of uBlock Origin for Microsoft Edge Legacy, extending the extension to a fourth browser platform. The port required modifications to work with Edge's extension APIs and was published on the Microsoft Store, replacing the previous sideloading requirement.
Mozilla Awards uBlock Origin 'Pick of the Month'
Mozilla recognized uBlock Origin with its 'Pick of the Month' award, highlighting the extension's efficiency, user privacy focus, and zero-monetization model. The recognition came as uBlock Origin was rapidly gaining market share from Adblock Plus among Firefox users seeking ad blockers without the Acceptable Ads program.
uBlock Origin Added to Debian 9 and Ubuntu 16.04 Repositories
uBlock Origin was packaged and added to the official Debian 9 and Ubuntu 16.04 repositories, making it installable through standard Linux package managers. This marked an important milestone for the project's reach into the Linux ecosystem and provided an alternative installation method outside browser extension stores.
uBlock Origin Completes Firefox WebExtensions Migration
The stable WebExtension version of uBlock Origin landed on Mozilla's Add-ons website, completing the migration from Firefox's legacy extension framework ahead of Firefox 57's November 2017 deadline. The migration required significant engineering work to port functionality to the new API, with some initial limitations compared to the legacy version.
uBlock Origin Fully Separated from Aljoudi's uBlock Project
Since October 2017, uBlock Origin became completely separated from Chris Aljoudi's uBlock project. The split was formalized after years of tension over the original uBlock project soliciting donations while no longer actively developing the software. In July 2018, ublock.org was acquired by AdBlock, closing the chapter on the original project.
German Supreme Court Rules Ad Blocking Is Legal
Germany's Federal Court of Justice (Bundesgerichtshof) ruled that ad blocking is legal in a landmark case brought by Axel Springer against Adblock Plus (I ZR 154/16). The ruling confirmed that users have the right to block ads and that Adblock Plus's whitelist business model was also legal. While uBlock Origin was not a party, the ruling affirmed the legality of the entire ad blocking ecosystem.
Google Proposes Manifest V3 Specification Threatening Ad Blockers
Google published the Manifest V3 specification proposing to replace the webRequest API with the more limited declarativeNetRequest API for Chrome extensions. The proposal would cap filter rules at 30,000 (later raised to 330,000) compared to the 300,000+ rules that advanced ad blockers employ. The EFF criticized the change as 'another example of the inherent conflict of interest' in Google controlling both Chrome and the largest ad network.
EFF Warns Google Against Hobbling Privacy Extensions with MV3
The Electronic Frontier Foundation formally presented Google with a list of concerns about Manifest V3, warning that the changes would break or hobble content blocking and privacy extensions. EFF staff technologist Bennett Cyphers called the webRequest API deprecation a direct threat to Privacy Badger and other tools that rely on dynamic network request interception.
Safari 13 Deprecates Legacy Extensions, Ending uBlock Origin Support
Apple's Safari 13 release with macOS Catalina deprecated the legacy Safari Extension API in favor of the restricted content blocker framework. uBlock Origin, which relied on the legacy API for its full functionality, became incompatible with Safari. The community-maintained Safari port by el1t had already stopped receiving updates in 2018.
Mozilla Commits to Supporting webRequest API Unlike Chrome
Mozilla published its Manifest V3 FAQ, confirming that Firefox would continue to support the blocking webRequest API alongside the new declarativeNetRequest API. This commitment differentiated Firefox from Chrome's approach and ensured that uBlock Origin's full capabilities would remain available on Firefox indefinitely.
CNAME Cloaking Tracker Bypass Technique Discovered
Researchers and uBlock Origin users identified a novel tracking technique where sites used CNAME DNS records to disguise third-party trackers as first-party requests, bypassing traditional ad blockers. The discovery prompted Raymond Hill to develop a countermeasure using Firefox's exclusive browser.dns API, which Chromium-based browsers could not replicate.
uBlock Origin Becomes First Extension for New Firefox Android
Mozilla announced that uBlock Origin was the first add-on available for the redesigned Firefox for Android (GeckoView), initially on Firefox Preview Nightly. This brought full ad-blocking capabilities to mobile Firefox users, a significant achievement given that Chrome for Android does not support extensions at all.
uBlock Origin v1.25 Ships CNAME Uncloaking on Firefox
uBlock Origin v1.25 introduced CNAME uncloaking, a Firefox-exclusive feature that performs DNS lookups on non-blocked resources to uncover and block first-party tracking domains disguised via CNAME records. The feature blocked approximately 70% of CNAME-cloaked trackers and was impossible to implement on Chromium browsers due to lack of a DNS lookup API.
Hill States He Will Never Transfer or Monetize the Project
Raymond Hill publicly stated on Reddit: 'I will never hand over development to whoever, I had my lesson in the past -- I wouldn't like that someone would turn the project into something I never intended it to become (monetization, feature bloat, etc.).' He added that at most he would archive the project and anyone could fork it under a new name.
Raymond Hill Ends uMatrix Development
Raymond Hill archived the uMatrix GitHub repository, ending development of the companion extension without announcement. The decision reflected Hill's prioritization of uBlock Origin over the more niche advanced filtering tool. uMatrix remained functional but received no further security patches, leaving it vulnerable to disclosed exploits.
uBlock Origin v1.40 Ships YouTube Ad Blocking Workaround for Chrome
uBlock Origin v1.40 introduced a workaround enabling the extension to block YouTube ads at browser startup on Chrome, addressing a longstanding issue where YouTube ads would slip through before the extension fully initialized. The fix demonstrated Hill's ongoing commitment to maintaining feature parity across browser platforms.
uBlock Origin Becomes Most Popular Firefox Add-on
uBlock Origin surpassed Adblock Plus to become the most popular Firefox add-on, representing 8% of all Firefox add-on usage. The achievement reflected a steady migration of users from Adblock Plus's paid whitelisting model to uBlock Origin's zero-monetization approach, with the Firefox version exceeding 5 million active users.
uBlock Origin Lite Published on Chrome Web Store for Manifest V3
Raymond Hill published uBlock Origin Lite on the Chrome Web Store, a stripped-down version built for Google's Manifest V3 framework. The lite version used the restrictive declarativeNetRequest API and lacked dynamic filtering, cosmetic exception filters, and the full range of capabilities of the original extension. Hill described it as a necessary concession to Chrome's new extension limitations.
YouTube Begins Anti-Adblock Campaign Targeting uBlock Origin Users
YouTube started deploying anti-adblock detection scripts that displayed popups warning users that 'ad blockers are not allowed on YouTube.' The campaign specifically targeted users of ad-blocking extensions including uBlock Origin, initiating a prolonged cat-and-mouse dynamic between YouTube's detection code and uBlock Origin's filter list maintainers.
YouTube Escalates Anti-Adblock with Fake Request Detection
YouTube significantly escalated its anti-adblock campaign by deploying fake network requests designed to detect whether ad blocker extensions were modifying responses. The new detection method initially defeated most ad blockers. uBlock Origin and AdGuard responded by updating their filter lists, but the arms race put significant strain on the two volunteer filter maintainers handling YouTube for uBlock Origin.
Google Confirms Chrome Will Disable uBlock Origin in 2024
Google confirmed that Chrome would disable Manifest V2 extensions including uBlock Origin as part of the Manifest V3 transition, with the phase-out beginning in June 2024. The announcement affected uBlock Origin's 29+ million Chrome users, who would need to either switch to the reduced-capability uBlock Origin Lite or migrate to Firefox or Brave.
Mozilla Reaffirms Permanent Manifest V2 Support for Firefox
Mozilla published an update declaring it had 'no plans to deprecate MV2 in the foreseeable future,' committing to support both the blocking webRequest and declarativeNetRequest APIs. The announcement differentiated Firefox from Chrome and secured uBlock Origin's full capabilities on the platform for the long term.
Chrome Begins Manifest V2 Phase-Out with Warning Banners
Chrome began displaying warning banners on the chrome://extensions page notifying users that Manifest V2 extensions including uBlock Origin would no longer be supported. The warnings appeared initially on Chrome's pre-stable channels (Dev, Canary, Beta) and gradually rolled out to stable. MV2 extensions lost their Featured badge on the Chrome Web Store.
DOJ Wins Landmark Ruling That Google Holds Search Monopoly
Judge Amit Mehta ruled that Google held monopoly power in general search engine services and text advertising, paying billions to device makers for default search status. The ruling provided broader legal context for Google's Manifest V3 changes, which critics described as leveraging Chrome's browser monopoly to protect its advertising revenue from ad blockers.
Mozilla Falsely Flags uBlock Origin Lite for Data Collection
Mozilla's add-on review team flagged every version of uBlock Origin Lite as violating its policies, falsely claiming the extension collected user data and contained 'minified, concatenated or otherwise machine-generated code.' Raymond Hill publicly debunked the allegations, stating 'it takes only a few seconds for anyone who has even basic understanding of JavaScript to see the raised issues make no sense.'
Hill Pulls uBlock Origin Lite from Firefox Store Over Hostile Reviews
Raymond Hill withdrew uBlock Origin Lite from Firefox's add-on store after a protracted dispute with Mozilla's review process, which he described as 'nonsensical and hostile.' Even self-hosted versions faced arbitrary delays, taking 5 days for approval notification. Mozilla later apologized and admitted fault, but Hill declined to reinstate the extension on the store.
Google Chrome Begins Disabling uBlock Origin for Users
Google began remotely disabling uBlock Origin on Chrome as part of the Manifest V2 phase-out, affecting the extension's 29+ million Chrome users. The extension was marked as deprecated on the Chrome Web Store and gradually removed from installations. Users received banners stating the extension 'may soon no longer be supported.'
Opera Commits to Independent uBlock Origin Support via MV2
Opera announced it would continue supporting uBlock Origin by independently maintaining Manifest V2 support in its Chromium-based browser, modifying the upstream codebase to keep MV2 extensions functional. This commitment joined Firefox and Brave in preserving the full uBlock Origin experience outside Chrome.
Pie Adblock Called Out for Copying uBlock Origin GPL Code
Pie Adblock, a for-profit browser extension from Honey co-founder Ryan Hudson, was exposed for incorporating uBlock Origin code and filter lists without proper GPL v3 attribution. The extension included uBlock Origin's Quick Fixes filter list and source code with licensing information stripped. Hill noted this was part of a broader pattern of commercial extensions rewrapping uBlock Origin with monetization schemes.
Microsoft Edge Begins Turning Off uBlock Origin MV2 Extensions
Microsoft Edge followed Chrome's lead and began disabling Manifest V2 extensions in its Canary builds, with uBlock Origin among the affected extensions. The timeline for stable channel cutoff remained 'TBD,' but the move signaled that Edge would eventually follow Chrome's MV3 transition, further reducing the platforms where full uBlock Origin remains available.
Chrome Permanently Disables All Manifest V2 Extensions
Chrome 138 permanently disabled all remaining Manifest V2 extensions, completing the phase-out that began in 2024. The full uBlock Origin extension became permanently unavailable on Chrome, with MV2 support fully removed in Chrome 139 even for enterprise users. Users were directed to uBlock Origin Lite or alternative browsers.
Brave Maintains uBlock Origin MV2 Support via Chromium Modifications
Brave confirmed its ongoing commitment to supporting uBlock Origin's Manifest V2 version by modifying Chromium's codebase to force-enable MV2 support. Users could access the full extension through Brave's settings menu under Extensions > Manifest V2 extensions, making Brave and Firefox the primary remaining platforms for the full uBlock Origin experience.