CatBlock is an ad-blocking extension, which replaces ads with cute pictures of cats (or whatever you want)!

What is CatBlock?
CatBlock is an ad-blocking extension for Firefox. It replaces ads with cute pictures of cats or any other images of your choice. Originally developed by AdBlock team in 2014, it was open-sourced and continued by Kieran and Tomáš. Get more information about its development and history on GitHub.
Users: 152 ▲ 6
Rating: 4.67 (12)
Version: 1.4.9 (Last updated: 2016-09-15)
Creation date: 2016-05-18
Weekly download count: 11
Firefox on Android: Yes
Risk impact: Very high risk impact
Risk likelihood: Low risk likelihood
Manifest version: 2
  • http://*/*
  • https://*/*
  • contextMenus
  • tabs
  • idle
  • webRequest
  • webRequestBlocking
  • webNavigation
  • alarms
  • storage
  • See more
Size: 1.14M
URLs: Website
Stats date:

Other platforms

Not available on Chrome
Not available on Edge
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In October 2014, when the original CatBlock extension was officially discontinued by Michael at AdBlock, and open-sourced under the GPLv3 license by AdBlock Team, Kieran and Tomáš (at that time members of AdBlock Team), decided to keep CatBlock alive independently.

Kieran & Tomáš left the AdBlock team in early 2016 to put more effort into development of CatBlock, including creating versions compatible with both Mozilla Firefox and Microsoft Edge.

For more information about the development & history, please check out

User reviews
Love seeing the cats instead of annoying ads!
by JacquelynSapphire, 2023-08-05
View all user reviews
Risk impact

CatBlock is very risky to use and it requires a lot of sensitive permissions. Avoid installing this add-on unless you absolutely trust this publisher.

Risk likelihood

CatBlock has earned a fairly good reputation and likely can be trusted.

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