µBlock, a lean and fast blocker

uBlock Origin (uBO) v1.66.4 was made available on 15-September-2025.
Download: Autoupdate or install from the browser's Add-ons source.

Homepage | Announcement, Release Notes & Downloads | Wiki | Release History | Documentation | Installation | Support |

Note: Though released by the uBO developer, reviews may still be pending with the browser developers.

Spoiler

• Fix potential infinite loop when scanning for $ anchor.
• Allow generic exception for replace= option.

 

Already available in MS for Edge.

 

uBlock Origin 1.66.4 is now available for Firefox, no longer pending.
(Firefox/ Extensions/ Manage extensions/ Tools for all add-ons (cogwheel)/ Check for Updates/ uBlock Origin 1.66.4 is offered)

 

Thank you!

 

Guys, is it just me, or do you also get to see more and more warnings on Google Search that you might be a robot? I wonder if it's caused by uBlock Origin?

 

In 2020, with uBlock Origin 1.25.0, "uBlock filters – Experimental" was removed from stock lists. [1] [2]

September 2025, with uBlock Origin 1.66.0, "uBlock filters – Experimental" was added to built-in filters again. [3] [4]

I wasn't able to find anything in the uBlock Origin Wiki, Issues, Pull requests, or Discussions, explaining why "uBlock filters – Experimental" was added again.

Did any of you find any documentation?
What is "uBlock filters – Experimental" for, exactly?

 

The experimental filters are filters being evaluated for inclusion in uBlock Origin's default set of filters. The goal of these filters is to lower page breakage in uBO.
The experimental filters are disabled by default, enable only if you want to help evaluate/fine tune these filters.
They are also available in uBoL.

P.S.

Instead, the web page for test filters is a mystery:

https://ublockorigin.github.io/uBOL-home/tests/test-filters.html

As you can see, it refers (also) to Firefox + uBO MV2.
But I don't understand the purpose.

 

Thanks very much, Sampei Nihira.
Yes, I noticed "uBlock filters – Experimental" are disabled by default. But I didn't understand what they were for. What you wrote, "enable only if you want to help evaluate/fine tune these filters," that was very helpful, thanks.

 

it was
"ublock works best with firefox"

meanwhile its:
"uBoL works better with firefox"

i have imported 100% of my adguard user rules at once (!) into uBoL, where ublock struggled.

 

It is still there (pinned)

 

uBlock Origin 1.67.0 is now available for Firefox, no longer pending.
(Firefox/ Extensions/ Manage extensions/ Tools for all add-ons (cogwheel)/ Check for Updates/ uBlock Origin 1.67.0 is offered)

 

Yeah, I get this a lot. A royal pain.

 

It's very annoying, I don't know if this is caused by uBlock Origin. Luckily I haven't seen it on Google Search that much, but when I sometimes visit other sites I get warnings from Cloudflare, they have to check if you're not a bot, quite ridiculous. I wonder if it's because of those AI scrapers.

 

I also get those Cloudflare warnings frequently these days, really annoying.

 

cloudflare is mandatory (server side security), not optional. if you get checked, then only once, until you delete cookies for that site.

 

The question is if we get to see these warnings because we use uBlock? For example, if you use anti-paywall extensions, websites sometimes think that you're a bot.