- Purpose & General Info
- Performance and Efficiency
- Release History
uBlock is not an ad blocker; it's a general-purpose blocker. uBlock blocks ads through its support of the Adblock Plus filter syntax. uBlock 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. uBlock'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 uBlock. Many more lists are readily available to block trackers, analytics, and more. Hosts files are also supported.
Once you install uBlock, you may easily un-select any of the pre-selected filter lists if you think uBlock blocks too much. For reference, Adblock Plus installs with only EasyList enabled by default.
 Details of the benchmark available at Firefox version: benchmarking memory footprint.
 Important note: 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.
uBlock 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 uBlock and others: Blocking ads, trackers, malwares.
Feel free to read about the extension's required permissions.
Safari 6.1 and later (developed on Safari 8/Yosemite; tested on 6.1/Mountain Lion and 7/Mavericks).
Note for all browsers
To benefit from uBlock's higher efficiency, it's advised that you don't use other inefficient blockers at the same time (such as AdBlock or Adblock Plus). uBlock 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.
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 uBlock on Crowdin.