uMatrix and Why You Should be Using it

4 min readMar 5, 2019

uMatrix running in Chrome on the YouTube trending page

What is uMatrix?

uMatrix is an open source browser extension for Chrome and Firefox that allows you to control a large part of your internet browsing experience. There’s a bit of a learning curve but once it starts coming together web pages will load faster, you’ll be safer and you’ll know exactly what is running when you load a website.

Above is a zoomed-in screenshot of the first image, showing the elements uMatrix permits you to allow or block.

Cookies - store information about the user, one common use is for logging into websites, cookies enable you to stay logged in until you choose to log out
CSS - the design of the site
image - allows or blocks images on the site
media - includes anything with <audio>, <video>, <object>, and<embed> html tags
scripts - processes that run in the background that the user doesn’t see
XHR - includes things like WebSockets that are constantly updating as a site is being used
frame - is everything within <iframe> or <frame> html tags
Other - anything not in the other categories

Why use uMatrix?

The Internet is Faster

Here are two images showing the Chrome developer tools network tab when I visited cnn.com. I loaded the page twice and watched for a little under a minute. Without uMatrix enabled, the site took over a second more to load, transferred over 5 times as much data, and there were nearly 5 times as many requests.

These differences might not seem like much for one site load, but the time adds up over the course of a month or a year.

The Internet is Safer

The internet is a scary place. It seems like every month or so there’s another huge data breach where millions of personal emails and passwords are stolen. The website have i been pwned maintains a list of sites that have been breached and the types of information stolen.

By default, uMatrix will allow any first-party domains to run. For example, when it is running and you visit this blog, anything from the domain medium.com is allowed, and anything else is blocked. This will break some websites at first (until you enable the right items in the uMatrix console), but what you get in return makes it worth your while.

All nefarious scripts and malware will automatically be blocked, letting you browse the internet at ease. Sometimes, trustworthy sites are hacked and have malicious code injected into them. uMatrix takes care of this problem for you outright by automatically blocking it.

Maintain Your Privacy

Ever look up something for a friend and proceed to get bombarded with ads for that thing for weeks afterwards? Not so with uMatrix! Third party trackers that use and sell your data such as Facebook’s pixel and Google’s AdWords will be blocked by default, meaning you will not be tracked as you surf the web.

Why is being tracked so bad? This article by the Electronic Frontier Foundation goes into more depth about it, but a few examples they give include Facebook manipulating Newsfeeds to see if it made users happy or sad, and their potential to track your location and network through dust or scratches on your camera.

Useful privacy settings in the uMatrix control panel

uMatrix also includes some optional settings that can enhance your privacy. Some sites can track you even if you consistently delete your cookies. They do this by using your browser’s cache, the cache being a way for your browser to store data locally (such as images) so that when you revisit a website, it loads faster by getting those resources locally instead of remotely. Luckily for us, uMatrix can clear our cache based on an interval of time that is customizable. (Click here to get a more in depth look on how browser cache tracking works).

Conclusion

If you’re able to withstand the learning curve of uMatrix you’ll be rewarded many times over with a faster, safer internet, and enhanced privacy. As time goes on, more and more services and apps are trying to track you and use your data for their benefit, so the best time to learn how to safeguard your internet browsing experience is now.