uBlock Origin - An efficient blocker for Chromium and Firefox. Fast and lean.
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There is an idea floating around that uBlock Origin is a lesser branch relative to uBlock[1].

The current reality is that there are two branches, not an official one and a lesser one. I keep developing my branch the same way and in the same spirit I have since the beginning of uBlock in June 23, 2014, so in substance uBlock Origin is the original uBlock.

uBlock Origin is completely unrelated to the web site ublock.org: the donations sought by ublock.org are not benefiting any of those who contributed most to create uBlock (developers[2], translators, and all those who put efforts in opening detailed issues). For the differences in features between uBlock Origin and uBlock, you are more likely than anywhere else to find an unbiased explanation in this Wikipedia article.

Somewhere toward the end of May, I decided I will not contribute code anymore to this uBlock branch.[3]

[1] An example. Another one.
[2] Keep in mind these charts do not take into account all the work done on the wiki (doc, benchmarks), which work was for the most part not contributed by the individual behind ublock.org.
[3] Reasons: this vs. this, and this, and overall because of serious incompatibilities in the spirit of the project.

uBlock Origin

pronounced you-block origin (/ˈjuːˌblɒk/) — you decide what enters your browser.
English, Chinese (中文), Korean (한국어)

An efficient blocker add-on for various browsers. Fast, potent, and lean.


uBlock Origin (or uBlock₀) is not an ad blocker; it's a general-purpose blocker. uBlock₀ blocks ads through its support of the Adblock Plus filter syntax. uBlock₀ extends the syntax and is designed to work with custom rules and filters. Furthermore, advanced mode allows uBlock₀ to work in default-deny mode, which mode will cause all 3rd-party network requests to be blocked by default, unless allowed by the user.

That said, it's important to note that using a blocker is NOT theft. Don't fall for this creepy idea. The ultimate logical consequence of blocking = theft is the criminalisation of the inalienable right to privacy.

Ads, "unintrusive" or not, are just the visible portions of privacy-invading apparatus entering your browser when you visit most sites nowadays. uBlock₀'s main goal is to help users neutralize such privacy-invading apparatus — in a way that welcomes those users who don't wish to use more technical, involved means (such as µMatrix).

EasyList, Peter Lowe's Adservers, EasyPrivacy and Malware domains are enabled by default when you install uBlock₀. Many more lists are readily available to block trackers, analytics, and more. Hosts files are also supported.

Once you install uBlock₀, you may easily un-select any of the pre-selected filter lists if you think uBlock₀ blocks too much. For reference, Adblock Plus installs with only EasyList enabled by default.

By the way, looks like I still need to dispel that other myth: I've seen in many places lately the following assertion:

ublock blocks ads just like adblock plus, but triggers the ads API to think it got viewed

Completely false. uBlock Origin does not "trigger" any "ads API" (whatever that is). It prevents network requests from being made according to filter lists so that your browser does not connect to remote servers, period.


Quick guide: popup user interface

For advanced usage, read about dynamic filtering and more on uBlock₀'s wiki.



On average, uBlock₀ really does make your browser run leaner. [1]

Chromium [2]


[1] Details of the benchmark available at Firefox version: benchmarking memory footprint.

[2] Important note: There is currently a bug in Chromium v39 to v41 which causes a new memory leak each time the popup UI of an extension is opened. This affects all extensions. Keep this in mind when measuring Chromium's memory usage. In the benchmarks, I avoided opening the popups completely.


uBlock₀ is also easy on the CPU

Details of the benchmark available in this LibreOffice spreadsheet.


Being lean and efficient doesn't mean blocking less

For details of benchmark, see uBlock₀ and others: Blocking ads, trackers, malwares.

Quick tests


Feel free to read about the extension's required permissions.


You can install the latest version manually, from the Chrome Store, or from the Opera store.

Firefox / Firefox for Android

Firefox Add-ons web site, or install manually by downloading the latest uBlock0.firefox.xpi file, and by dragging the downloaded xpi file to your add-on page.

Of interest: Deploying uBlock Origin for Firefox with CCK2 and Group Policy.


There is no support for Safari for uBlock Origin.

Best is that you install chrisaljoudi/uBlock, which has official support for Safari.

Note for all browsers

To benefit from uBlock Origin's higher efficiency, it's advised that you don't use other inefficient blockers at the same time (such as AdBlock or Adblock Plus). uBlock₀ will do as well or better than most popular ad blockers.

Release History

See the releases pages for a history of releases and highlights for each release.


uBlock Origin's manifesto.

Free. Open source. For users by users. No donations sought.

Without the preset lists of filters, this extension is nothing. So if ever you really do want to contribute something, think about the people working hard to maintain the filter lists you are using, which were made available to use by all for free.

You can contribute by helping translate uBlock₀ on Crowdin.