This is the best Firefox add-on ever!
In my opinion should be a must, a FF built-in.

I read that the author uses UBlock, rather than UMatrix. It is not my case, and would like to share my logic:
UBlock is a great add-on too. However, if you use a more friendly granulated firewall (UMatrix), you avoid most of the ads, trackers, scripts etc. Doesn't make sense to use a more generalist firewall (UBlock), and at the same time having to add lot of filtering hosts/lists that reduce browser performance. The main filter should be the firewall itself, rather than the hosts/lists.
UMatrix well configured will block most of the stuff, without adding hosts/lists, and increasing browser performance.

Some users say that UMatrix "is difficult to understand, to learn, to configure etc", but this is not true.
The problem is not the add-on, but the user! Users don't want to read, to learn, to understand, to configure etc... they just want to install & use. The point is that UMatrix-wiki doesn't take maximum more than 15 minutes to be read, and another maximum 15 minutes to learn how to use it. Considering that UMatrix will work like 3 or 4 different add-ons at the same time, I prefer UMatrix taking me 30 minutes, rather than 4 different add-ons taking me 60 minutes or killing the browser performance.
And those users complaining about UMatrix breaking this or that... seriously... or they don't know how to use it, or they want the impossible (a firewall that blocks everything without blocking nothing).

My dream and request are:
1) A simple "disable option" at the main-panel, without white-listing (it is very unpractical to do it trough FF add-on page).
2) A real-time cloud malware/antivirus/phishing/ransomware etc service option.
3) A blocking ads and trackers/tracking not by hosts/lists, but by encoded rules (like "BluHell", "Privacy Protector" etc).
4) Same UBlock dashboard options in UMatrix dashboard. Another possibility (and perhaps easier) might be making UBlock firewall more friendly granulated as UMatrix.
5) Incorporation of same special NoScript filters, increasing security capabilities in unlocked-firewall.
For this dreamed add-on... I will be more than happy to make a fat donation!

Thousand thanks to the author!

Great replacement for NoScript, thumbs up!

Thanks Mozilla for breaking NoScript. Wouldn't have found uMatrix without it. With NoScript, I essentially had to reload pages to Chrome to get 'em to work. Now I can SEE what exactly is going on and give permissions as I need to.

I'm using block all / exceptions. https://github.com/gorhill/httpswitchboard/wiki/How-to-use-HTTP-Switchboard:-Two-opposing-views is definitely required reading.

Addon poderoso que bloqueia solicitações de conexões indesejadas, conforme o próprio desenvolvedor, é para usuários avançados, mas nada impede que você se adapte aos poucos e aprenda muito do que acontece "por trás das cenas". Hoje, para mim, é indispensável e insubstituível. Eu poderia ficar sem qualquer outra extensão para privacidade, uMatrix supre todas as necessidades que tenho. Ainda estou aprendendo. Perfeito !

I've been using ad-hoc blocking methods in different addons for some time. uMatrix combines them all very neatly and conveniently. (And it's now on Android too!)

Brilliant!

THE BEST OF THE BEST IN THE WORLD....POINT !

it's for something that understands networking and how internet, DNS, SOA and all related things !

تشکر.عالی

Install version 1.0.0 of uMatrix:
https://addons.mozilla.org/de/firefox/addon/umatrix/versions/?page=1#version-1.0.0

Open the uMatrix Dashboard, all your settings and rules should be there. Now export these settings to a file, update to the latest Version of uMatrix and import the settings from the file you've just saved. Enjoy!

uMatrix is a great addon and I'm glad that the devs put in the effort to switch to web extensions. Your work is highly appreciated :)

First of all: people, read the bloody info!
Although you think you get it, although you think you can handle it...
Gorhil is pretty clear (and correct) about it:
*** uMatrix IS NOT FOR EVERYBODY...
RTFM!

As for the coding/ addon: been using it for a while now, and it is perfect! Yes, it breaks stuff sometimes. But then again, that's why you installed it for in the 1st place, right?
Confused? Don't get that last statement?
OK, if you can't figure that out, return to ***
...
Don't say they didn't warn you. ☺

BTW, if you DO know what this is all about, uMatrix works brilliantly with Gorhills (now new) uBO-Scope, because it shows you what those cryptic URLs actually do. So you can block them, if you want. You know, break stuff... Works for me!

Gorhill: I know you don't take feature requests, but concerning uMatrix... If you come over the code (you know, because you're there any way) which defines the name of the backup (settings/ rules) file... Can you please make it add the current date and time, just like with the backup files for uBO? Would be immensely helpful. Enables to keep a small backlog of previous configurations without renaming the files. I know, nothing xdotool on my box can't automate, but still... Cheers...

Brilliant that this is now photon-compatible, thanks.

However, it seems to have lost my previous uMatrix profiles, so several sites refused to render or to work properly (including addons.moz comments!) until I updated them. Ouch.

That's a bit careless, with no notification. But I sort of understand, and it's a little unfair to criticise after all the work Raymond has done. I blame moz more for the dog's breakfast approach.

Very puzzling until I worked it out. And I had been complaining about Nightly developers, too, releasing a version that didn't render properly, when it was the unannounced uMatrix update that did it.