uBlock Origin

uBlock Origin

uBlock Origin pop-up interface
Original author(s)	Raymond Hill (gorhill)
Developer(s)	Current: Raymond Hill Past: Deathamns, Chris Aljoudi, Alex Vallat[1]
Initial release	June 23, 2014; 10 years ago (2014-06-23)[2]
Stable release	1.60.0[3] / 26 September 2024; 34 days ago (26 September 2024)
Repository	github.com/gorhill/uBlock
Written in	JavaScript
Operating system	Cross-platform
Available in	72[4] languages
Type	Browser extension
License	GPLv3
Website	github.com/gorhill/uBlock

uBlock Origin (/ˈjuːblɒk/ YOO-blok^[5]) is a free and open-source browser extension for content filtering, including ad blocking. The extension is available for Chrome, Chromium, Edge, Firefox, Brave, Opera, Pale Moon, as well as versions of Safari before 13.^[6] uBlock Origin has received praise from technology websites and is reported to be much less memory-intensive than other extensions^[7][8] with similar functionality.^[9][10] uBlock Origin's stated purpose is to give users the means to enforce their own (content-filtering) choices.^[11][12]

uBlock Origin is actively developed and maintained by its creator and lead developer Raymond Hill and the open source community.^[1] As of October 2024^[update], the Chrome version of uBlock Origin had over 40 million active users and the Firefox version had over 8 million active users.^[13][14]

uBlock was initially named "μBlock" but the name was later changed to "uBlock" to avoid confusion as to how the Greek letter μ (Mu/Micro) in "μBlock" should be pronounced.^{[citation needed]} Development started by forking from the codebase of HTTP Switchboard along with another blocking extension called uMatrix, designed for advanced users.^[15] uBlock was developed by Raymond Hill to use community-maintained block lists,^[16] while adding features and raising the code quality to release standards.^[17] First released in June 2014 as a Chrome and Opera extension, in 2015 the extension became available in other browsers.^{[citation needed]}

A joint Sourcepoint and comScore survey reported an 833% growth from November 2014 to August 2015, the strongest growth among adblockers listed.^[18] The report attributed the growth to the desire of users for pure blockers, outside the "acceptable ads" program operated by Adblock Plus.^[19]

On April 3, 2015, Hill transferred the uBlock project to Chris Aljoudi due to frustrations with dealing with requests as the project's popularity increased.^[20] "These projects are to me, not a full time job. It stopped being a hobby when it felt more and more like a tedious job. I will keep maintaining my version (and share with whoever care[s] to use it) because it guarantees the tool will match what I want out of it."^[21] Hill created his own fork and renamed it uBlock Origin on April 6.^[22]

Since October 2017, uBlock Origin has been completely separated from Aljoudi's uBlock.^[23] Aljoudi created ublock.org to host and promote uBlock and to request donations. In response, uBlock's founder Raymond Hill stated that "the donations sought by ublock.org are not benefiting any of those who contributed most to create uBlock Origin."^[6] The development of uBlock stopped in August 2015 but there were sporadic updates from January 2017.^[24]

In July 2018, ublock.org was acquired by AdBlock and resumed development.^[25] From February 2019, uBlock began allowing users to participate in "acceptable ads",^[26][27] a program run by Adblock Plus that allows some ads deemed "acceptable" and nonintrusive, and for which larger publishers pay a fee.^[28]

uBlock Origin remains independent and does not allow ads for payment.^[29] The project refuses donations and instead advises supporters to donate to maintainers of block lists.^[30] Hill continued to work on the extension under the name uBlock Origin, abbreviated as uBO^[31] and originally as uBlock₀.^[32]

In January 2016, uBlock Origin was added to the repositories for Debian 9 and Ubuntu 16.04.^[33][34] The extension was awarded "Pick of the Month" by Mozilla for May 2016.^[35]

On December 11, 2016, Nik Rolls released a fork of uBlock Origin for the Microsoft Edge browser (now known as Microsoft Edge Legacy).^[36] In April 2020, this fork was deprecated as Microsoft replaced Microsoft Edge Legacy with a Chromium-based Edge.^[37]

In 2023, Google made changes known as "Manifest V3" to the WebRequest API used by ad blocking and privacy extensions to block and modify network connections.^[38][39] Following Google's implementation of Manifest V3 and the end of support for V2, uBlock Origin's effectiveness is drastically reduced in Google Chrome and other Chromium-based browsers.^[40][41][42]

As a result, uBlock Origin Lite was created and designed to comply with the Manifest V3 (MV3) extension framework. uBO Lite differs significantly from uBO in several key aspects, primarily due to the constraints and design goals associated with MV3. Specifically, it lacks filter list updates outside of extension updates, and has no custom filters, strict-blocked pages, per-site switches, or dynamic filtering. Non-Chromium browsers such as Firefox are unaffected.^[43] Google has been criticized for implementing some of these features due to its domination in the online advertising market.^{[44][45][46][47]}

As of October 2024, the Chrome version of uBlock Origin Lite has over 700,000 active users.^[48]

uBlock Origin supports the majority of Adblock Plus's filter syntax. The popular filter lists EasyList and EasyPrivacy are enabled by default. The extensions are capable of importing hosts files and a number of community-maintained lists are available at installation. Among the host files available, Peter Lowe's ad servers & tracking list and lists of malware domains such as uBlock Origin's own anti-malicious filter called Badware risks are also enabled as default, preventing users from visiting malicious websites such as those used for phishing, scams, malware, and more.^[49] Some additional features include dynamic filtering of scripts and iframes and a tool for webpage element hiding.^{[citation needed]}

uBlock Origin includes a growing list of features not available in uBlock, including:

• A mode to assist those with color vision deficiency.
• A dynamic URL filtering feature.
• Logging functionality.
• Interface enhancements including a DOM inspector, privacy-oriented options to block link prefetching, hyperlink auditing, and IP address leaks via WebRTC (this feature was removed in version 1.38 on all platforms except Android, as most browsers are no longer vulnerable^[50]).

Site-specific switches to toggle the blocking of pop-ups, strict domain blocking, cosmetic filtering, blocking remote fonts, and JavaScript disabling were also added to uBlock Origin.^[51] The Firefox version of uBlock Origin has an extra feature which helps to foil attempts by web sites to circumvent blockers.^[52]

Technology websites and user reviews for uBlock Origin have regarded the extension as less resource-intensive than extensions that provide similar feature sets such as Adblock Plus.^[53][54][55] A benchmark test, conducted in August 2015 with ten blocking extensions, showed uBlock Origin as the most resource-efficient among the extensions tested.^[56]

uBlock Origin surveys what style resources are required for an individual web page rather than relying on a universal style sheet. The extension takes a snapshot of the filters the user has enabled, which contributes to accelerated browser start-up speed when compared to retrieving filters from cache every time.^[57]

Starting with version 1.54, uBlock Origin introduced the implementation of differential updates (delta updates), which allows the extension to fetch only changes to filter lists rather than downloading the entire list. This results in lower bandwidth consumption and more frequent updates. This change was part of uBlock Origin’s efforts to reduce both requests and bandwidth usage, with the goal of not being ranked among the most bandwidth-intensive projects on jsDelivr, as reflected in public statistics.^[58][59]

According to a research paper, uBlock Origin was able to reduce web page load times by 28.5%, the highest efficiency compared to other ad blockers like AdBlock Plus and Privacy Badger. Its use could significantly reduce energy consumption, saving an estimated 100 hours of browsing time annually for the average global user.^[60]

If widely adopted in the United States, it could save over $117 million per year in electricity costs, and globally, it could result in savings exceeding $1.8 billion. The research report also suggests that widespread use of uBlock Origin could have environmental benefits, potentially preventing pollution-related deaths caused by coal-fired power generation used to support the extra energy consumption from ads.^[60]

According to the creator and lead developer Raymond Hill of the extension, uBlock Origin works best on Firefox.^[61] The main reason is that uBlock Origin (uBO) faces several technical limitations when used on Chromium-based browsers compared to its performance on Firefox, and as a result, users may experience less effective ad blocking, potential exposure to unwanted content, and slower performance when using uBO on Chromium-based browsers:^[62]

In November 2019, a uBlock Origin user reported a novel technique used by some sites to bypass third-party tracker blocking. These sites link to URLs that are sub-domains of the page's domain, but those sub-domains resolve to third-party hosts via a CNAME record. Since the initial URL contained a sub-domain of the current page, it was interpreted by browsers as a first-party request and so was allowed by the filtering rules in uBlock Origin (and in similar extensions). The uBlock Origin developer came up with a solution using a DNS API which is exclusive to Firefox 60+.^[63] The new feature was implemented in uBlock Origin 1.25, released on February 19, 2020.^[64]

Chromium-based browsers lack the ability to uncloak third-party servers disguised as first-party through CNAME records. This limitation reduces the efficiency of blocking third-party trackers, a capability that uBO fully utilizes on Firefox.

Furthermore:

• IP address filtering: In version 1.60, uBO introduced the ability to block network requests based on their IP addresses. This is achieved by fetching the DNS records for a specific URL and filtering according to the IPs found. Full support is available for Firefox-based browsers, while Chromium-based browsers can only filter when an IP address is directly used in the URL instead of a hostname.
• HTML Filtering: uBO's ability to filter the response body of HTML documents before they are parsed by the browser is hindered in Chromium-based browsers. This feature, enabled by the webRequest.filterResponseData() API, is currently only available in Firefox, limiting the effectiveness of uBO's HTML filtering on Chromium-based platforms.
• Response Body Filtering: The replace= option in network filtering, which allows for response body modification, is less effective in Chromium-based browsers. Firefox's support for this feature enables more robust content manipulation.
• Browser Launch Filtering: On Chromium-based browsers, uBO may not be fully ready to block network requests from already opened tabs immediately upon browser launch. This can allow some tracker or advertisement payloads to load before uBO becomes active, which is especially problematic for users who utilize default-deny modes for third-party resources or JavaScript. While there is a mitigation setting available, it is not enabled by default and does not cover all use cases.
• Pre-fetching: In Chromium-based browsers, websites may override user settings regarding pre-fetching, potentially leading to unwanted network requests. Firefox, in contrast, reliably prevents pre-fetching when it is disabled in uBO.
• WebAssembly Usage: uBO does not use WebAssembly for core filtering code paths on Chromium-based browsers due to the additional permissions required in the extension manifest, which could complicate the extension's publication in the Chrome Web Store. This limitation can affect performance and functionality.
• Storage Compression: uBO on Chromium-based browsers cannot effectively use LZ4 compression for storing filter lists and other data due to issues with IndexedDB in incognito mode. IndexedDB instances are reset in incognito mode, causing uBO to start with out-of-date filter lists and reduced efficiency. Firefox does not face this issue, allowing for more efficient storage and retrieval of data.

uBlock Origin is actively developed for applications based on two major layout engines.^[16][53][65]

• Blink
  • Google Chrome/Chromium (desktop)
  • Brave (desktop)
  • Opera (desktop)
  • Microsoft Edge (Chromium) (desktop)
  • Kiwi (mobile)^[66]
• Gecko
  • Firefox (desktop: 0.85.5 and later)^{[note 1]}
  • Firefox for Android (mobile: 0.9.1.0 and later)
  • Thunderbird (desktop: 1.3.0 and later)
  • SeaMonkey

• WebKit
  • Safari (desktop: uBlock Origin 1.10.0 and later (Beta)).^{[67][note 2]} Stopped working with macOS 10.15 Catalina and Safari 13.^[68][69]
• EdgeHTML
  • Microsoft Edge (legacy) (uBlock Origin is available on the Windows Store in beta from 1.10.0).^{[37][36][note 3]}

• NoScript
• Privacy Badger

Wikimedia Commons has media related to UBlock.

• Official website
• uBlock Origin on the Chrome Webstore