uBlock Origin uBlock Origin

Finally, an efficient wide-spectrum content blocker. Easy on CPU and memory.

uBlock Origin is a featured Firefox add-on by Raymond Hill. It has 5,790,213 daily active users and an average rating of 4.77. The latest version is 1.44.4 and was updated a day ago. Within Firefox Browser Add-ons, its overall ranking is #1.

uBlock Origin is not an "ad blocker", it's a wide-spectrum content blocker with CPU and memory efficiency as a primary feature.


Out of the box, uBO blocks ads, trackers, coin miners, popups, etc. through the following lists of filters, enabled by default:
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Risk impact

uBlock Origin requires a lot of risky permissions and is not safe to use. Avoid installing this add-on unless you absolutely trust this publisher.

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypass your security settings, and access your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Risk likelihood

uBlock Origin has earned a good reputation and can be trusted.

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Browser Add-ons, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on, especially ones with higher risk impact and/or higher risk likelihood.

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User reviews
by Ceran Vasse, 2022-09-30

by SAINT, 2022-09-29
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The manifest file declares the requirements and permissions that a Firefox add-on will have access to. By reviewing the manifest, you may be able to determine if a Firefox add-on is over-reaching (for example, if an extension is overriding your new tab page, or search provider, or requesting access to your web activities without any good reason).

  "author": "Raymond Hill & contributors",
  "background": {
    "page": "background.html"
  "browser_action": {
    "browser_style": false,
    "default_icon": {
      "16": "img/icon_16.png",
      "32": "img/icon_32.png"