uMatrix: A Desperately Needed User’s Guide

By | November 18, 2015

“Point & click to forbid/allow any class of requests made by your browser. Use it to block scripts, iframes, ads, facebook, etc.”

When I started using Google Chrome more, I realized there wasn’t a NoScript (different from a pop-up blocker) plugin available like there is for Firefox (update for 57 soon). After doing some research, I found many users recommended uMatrix – a beefed up ad-blocker, which was forked from HTTP Switchboard. So I tried it out, and my first impression while using it was: “I have no idea what I am doing.” Fortunately, I persisted with using it because it is a lot simpler than it appears. I wasn’t too impressed with the alternatives based on the feedback and reviews from the webstore. I found that after you spend some time learning how it works and customizing the settings based on your browsing tendencies, it is actually a manageable and powerful alternative to Firefox’s NoScript. I’ll break down the core functionality of the plugin to spare you the painful learning curve of uMatrix.

The Basics:

  1. “That huge box that comes up – I don’t know what any of it is.” – Neither did I, entirely. But as I began learning more about web development from launching this blog, I realized it is actually quite simple: webpages are made up of (the columns) cookies, CSS (cascading style-sheets), images, scripts, frames, XHR and other types of code. Webpages also contain code from many different websites (the rows), which easily adds up to a grid of 8×8 or bigger resulting in 64 or more individual squares to click. Yeah, it gets busy. You only need to know a few of those, though.
  2. You can save your exceptions/rules. Don’t want cookies to be collected on one site, but they’re required on another? No problem, click the uMatrix icon next to the address bar, click the top half of the square where the cookie column and domain row intersect, then click the lock icon in the top row. Done. Not too bad huh? The same principle applies towards entire domains, listed in each row. If you click the top half of the domain name, the entire area should turn green and thus be ‘whitelisted’.
    1. note: to set “global” whitelist/blacklist rules, click the very top left rectangle area and select the asterisk “*” symbol. Make any desired changes and click the lock icon to save all temporary changes. Thanks to tengen for commenting below about that helpful tidbit, should save someone some time.
  1. “So what is the bare minimum I need to know?” By default, uMatrix blocks most things and will, at first, reduce the functionality of your browser and even hinder your ability to fully utilize a website by only loading part of the content. By adding exceptions one at a time, your browser with uMatrix is taking the least amount of risk necessary for your specific needs. For instance, I know that on StumbleUpon, all the content is contained within some frame code, so I simply allowed all frame content to load on the domain by clicking the top half of the “frame” square. Now I can use that website safely. Other pages are more convoluted and take a bit of experimenting to correctly add permissions.


Additionally, many popular websites like Twitter have content offloaded to other sub domains or similar sounding domain names, e.g., I have to allow code from “” to allow the “Who to follow” box  to load because that’s how they designed their site. You must refresh the webpage after adding new exceptions. Other times it is less clear what needs to be allowed. Almost every time, CAPTCHAs (“Completely Automated Public Turing test to tell Computers and Humans Apart”) are embedded and load from some random domain name – you’ll need to find which one it is to get through the verification. The Google sponsored CAPTCHAs (they are conspicuously designed like advertisements) are the only ones I really have trouble with, because I find myself making an exception, refreshing, discovering more code embedded within that code, allowing it and refreshing again. . . It quickly becomes exhausting and going this far to maintain security and privacy means you really value those things or are very patient. Or both.

Taking it further:

The documentation on Github goes in depth, showing how to create your own rulesets. Go to the options menu for the extension in your browser, click edit, then type in “” “type” “allow/block”, like shown in the picture. Or just copy paste the sample rules provided in the link, your call. Adding exceptions graphically like I explained earlier is the equivalent of doing this.uMatrix options menu


There are “known bad domains” where less than reputable denizens of the web reside, or rather, where malware has been packaged into some trap. Thankfully there are people who document this kind of stuff and maintain lists of these bad domains. Also in the options menu, is the hosts file, which contains several of these lists and automatically blocks any request sent there (on purpose or accident).

User-Agent Spoofing:

When you load a webpage, you automatically submit some identifying information like browser type/version and operating system. Some people could care less, but the fact of the matter is that these small pieces of information can be combined with other small pieces to reliably identify who you are. The developer cited this publication. It is off by default, but can be enabled with one click. It works by giving shuffled common browser and operating system information in place of your real information. Be careful though, while your privacy and security are certainly important, not all websites are run by bad guys. User information and advertisements are crucial for analyzing traffic and providing revenue to fund the servers, so consider toggling off your incognito practices when visiting websites you support and trust.

19 thoughts on “uMatrix: A Desperately Needed User’s Guide

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  3. retrocycler

    Hi thanks for this guide.

    I’ve been using uMatrix on Chrome for good part of a year, but finally I think my patience is running out. The problem is that no matter where I go on the internet, if I go to a new page – one that uMatrix has not seen before, ergo is not in the ruleset – then I have to go through the “grid” giving permissions to ALL THE SAME DAMN domains (youtube, googlevideo, etc.) that I have by now marked up as permissible probably a thousand times.

    Why is it that uMatrix needs new permissions to be set for every little thing on every new page visited, even though it should know by now that I will want permissions from certain domains, no matter what page I’m on?

    I realize you are not the developer, but this is the only page I’ve found online where the use of uMatrix is being discussed, and I’m hoping to find a few other souls with the same problem.



    1. transposedmessenger Post author

      Hi RC, you’re welcome, and thanks for commenting! You are most certainly not alone, the UI is a bit more complex than traditional ad blockers and so it takes some getting used to. Just to make sure, are you clicking the top half of the rectangle with the domain name (the row title, I guess)? After you do that, are you saving the changes by clicking the lock icon at the top?

      1. tengen

        Hopefully you will see this 🙂

        You can set the permissions on all sites.

        What you need to do is click in the top left of the ui next to the power symbol, where it has the domain of the current site, and bring the little drop down and select *. Then set whatever sites to green/red. This will apply it to the global scope (everywhere) and not just the current domain.

        Hope this helps.

        1. transposedmessenger Post author

          Okay, so when I did that with Pinterest, I selected “” below the asterisk, which whitelisted all columns for the pinterest domain. Below that, there was “” which allowed javascript and frames to run on the page (but not javascript and frames from advertising domains). That’s a very quick way to adjust settings for websites, thanks for posting!

      2. TonyJ

        transposedmessenger, thanks for this reply. I spent an hour going to common sites I used and clicking the box to allow things. Restarted browser later and all settings were back to default. Got ready to dump uM, but did a quick search and found this. The Lock icon! solved it. Had no clue or even what a scope is, but all is so much easier now. And this is a great and powerful addon ( once Locked 😛 ) thx again!

          1. TonyJ

            Yes, I never heard of uMatrix, until NoScript no longer worked. I think I’ll keep uMatrix though. It’s really easy and powerful once I got over the lock thing. And to me, clicking the boxes is easier then clicking a long list of Noscript things to allow once or click to make them perm, then reload and click some more in the list.

          2. transposedmessenger Post author

            Yeah, I think it’s easier too and finely grained to boot. Also, sometimes you don’t want it to reload if you’re in the middle of a form or comment or something.

    2. Spyder Z

      Just in case you don’t get updates when sub-comments are made, do as tengen below is mentioning. Anything that you want to work on every site, just switch over to the global scope before setting it, and then save that scope. Boom , problem solved. Now you’ll only ever have to set up new sites with new domains in future. ;P

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  5. newyork10023

    I am unclear how uMatrix and uBlock Origin interact. I saw mention of uBO as a “pattern matcher” by the author, but this seems a gross simplification at best. I would prefer to dump uBO for uM (in a heartbeat), but uM doesn’t also support nearly as many filter lists (although it might be possible to include them by URL, ugh).

    1. Arno

      Several users reported and also the developer admits that uMatrix and uBlock can be used together, uBlock as an ad-blocker (with static filters) and uMatrix as a kind of firewall. If you intend to do that, disable dynamic filtering in uBlock by unchecking “Advanced user” and also uncheck in the Filterlist those filters that are already in use with uMatrix (Not vice versa, uMatrix is your mainstay for malware).

  6. Nick

    I think the author of uMatrix could save a lot of confusion if he used a different icon other than a lock for saving changes. It would never occur to me that clicking on a lock icon would save my changes, had I not stumbled across this page.


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