_{pronounce you-block as in "you decide what enters your browser" / see the "µ" as a stylish "u", to emphasize small resource footprint}
^{sorry for the dubious name, we are coders, not marketers}

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

• Purpose & General Info
• Performance and Efficiency
  • Memory
  • CPU
  • Blocking
  • Quick tests
• Installation
  • Chromium
  • Firefox
  • Safari
• Release History
• Wiki

µBlock is not an ad blocker; it's a general-purpose blocker. µBlock blocks ads through its support of the Adblock Plus filter syntax. µBlock extends the syntax and is designed to work with custom rules and filters.

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. µBlock'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 are enabled by default when you install µBlock. Many more lists are readily available to block trackers, analytics, and more. Hosts files are also supported.

On average, µBlock really does make your browser run leaner

^{Details of the benchmark available in this LibreOffice spreadsheet.}

^{Important note regarding memory usage: There is currently a bug in Chromium 39+ 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.}

µBlock 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 µBlock and others: Blocking ads, trackers, malwares.}

• Index
• Web page components
• Popups

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

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

You can install by downloading the latest uBlock.firefox.xpi file, and by dragging the downloaded xpi file to your add-on page.

You can get µBlock for Safari (Yosemite's 8.0 or newer) from the Safari Extension Gallery.

^{There are currently no plans to support older Safari's. It's not recommended that you install µBlock on them (do it at your own risk).}

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

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

µBlock's functionality is self-explanatory and intuitive for the most part. One thing to note after you get started is the big power button in µBlock's popup:

The big power button is to disable/enable µBlock for the specific current site/hostname (as extracted from the URL of the current page).

In other words, it applies to the current site only; it is not a global power button. The state of the power switch for a specific site will be remembered.

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

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 to translate this project. There's an entry on Crowdin where you may contribute to µBlock's localization.

GPLv3.