Zen Browser is a Firefox based browser whos developers say it is focused on design, privacy and user experience. Here’s my take on it.

For context: I have only tested Version 1.17.3b packaged as a flatpak. I tested it on two different desktop environments (Cinnamon and KDE Plasma). I have not tested for compatibility with screen readers.

Overview

Pro	Con
Clean UI	Doesn’t use system colours
Removes most of Mozillas ad-tracking	Doesn’t use system window decorations
Has a great page for customising shortcuts	Has no buttons for window controls visible by default
Firefox based	It has a really long onboarding process for which there is no obvious way to be skipped
	Weird defaults: Enables “Do Not Track”, which ironically is used for fingerprinting. Uses standard privacy profile Cookies are stored and not deleted History is stored and kept between browser restarts DNS isn’t secured Asks to store passwords, locations and credit card information. This should be kept separate from the browser for security reasons. Doesn’t enforce HTTPS Default search engine is Google By default the full URL isn’t visible The suggested pinned tabs and shipped bookmarks are not privacy friendly and not relevant to many users. By default will ask to be default browser on startup
	Has no letterboxing support.
	Has Firefox Accounts not disabled.
	Has a weird recommendation on new tab for “http://tagesschau.de” even though my system is set to English language.
	Doesn’t use the OSs language correctly. In my case EN_US instead of EN_GB.
	Has no advanced tracking protection through add-ons like uBlock or Privacy badger by default.
	Makes itself default for HTML files without asking
	Doesn’t remove Desktop entries on uninstallation.
	Minor: Source isn’t hosted on a Free [1] platform.

Setting up Zen and my experience during the process

Firstly, let me talk about the positive things. I really like the clean look of the browser and like that there are easy custamisation options already in the startup wizard.

Let me walk you through my experience setting up Zen.
Opening up Zen for the first time a big window pops up and then scales down to a smaller one. The small window is on Plasma not in the centre of the screen but at some random position even though plasma will centre new windows. On Cinnamon the window started centred. There is only a single button for going forward in this window. There are no controls for closing it. I know there are always keybinds for that, but it should be possible without them, seen from a usability perspective for casual users [2]. Furthermore I don’t appreciate that it isn’t consistent with the rest of the desktop environment in that it doesn’t use the default window decorations, or the colours I set for the desktop, although the latter might be because of Flatpak behaving weird.

Clicking on the arrow to get to the next window triggers an animation to a maximised window, which asks you if you want to set Zen as default browser and if you want to try import data from a previous browser. As it wouldn’t be able to import anything being in the Flatpak container I skipped this and didn’t set it as default.
The next screen asks to set the default search engine. The options are: “Google”, “Bing”, “DuckDuckGo”, “Ecosia” and “Perplexity”. Here I wonder: Where is the privacy? Sure DuckDuckGo is okay ish, but it would have been great not having Google as the option selected by default as well as having a private search, like a SearXNG instance or Startpage. I selected Ecosia as the only European option.

The next screen was very confusing to me at first. The feature of pinned tabs is a Firefox native one since not long ago, but the styling of the selection here in the setup screen isn’t intuitive to me. I was able to figure out that the different colouring in the borders was because of the icon colours, but it took me a moment to realise this was an interactive panel; which might be a me problem. But I have to things that are besides my stupidity still not really nice about this. Firstly you can’t just skip without pinning anything and the second is that the pin options aren’t good. Not a single of the default options is privacy friendly and some aren’t really user friendly too [3] [4] [5], which both I would not have critisised, if Zen didn’t advertise to be privacy and user friendly. I deselected all and hit next.

Following is a screen for customisation. I generally really like this, I’ve a small suggestion: add a skip button that will keep the default. If you don’t input anything the next button won’t do anything, but it would still be nice. Also why not take the desktops default colours here? Maybe that is a flatpak problem, but still seems weird to me. This is a feature present in most Linux DEs and even Windows has an accent colour and it would be really cool to see that integrated here.

Then a useless screen that tells me everything is set follows, just to have to hit another next button. Pressing that plays some nice animations, that could have been skipped. I want to use a browser not look at animations.

The first thing I notice: I can not see the whole URL. This is a security problem, since there are redirect links on for example google pages, which would just bee visible as google.com.
Then I notice: Why is there a folder in the tab area with Shitter ¹ and Reddit things from Zen? I want to use a browser, not have its self advertisement in it. I deleted the folder.
Now I want to go into settings. So I press CTRL+T to create a new tab and a search popup opens. I didn’t intend to search. What is the shortcut for just opening a new tab? Oh okay, the popup is just the nav bar of the new tab? This isn’t really obvious. So let me enter about:preferences.
Entering the settings and oh my, this is a place with good and bad sides. Why aren’t the settings centered on screen, but only in their container? Why does the settings navigation take up so much space? Okay, let me not complain further about these little things. Really, mostly I like the settings. I’d describe them as Firefox+, since that is what they are: the default Firefox settigns and a bit more.
Now let me see if I can get a way to display the full URL. Yes, it wasn’t hard too. Why didn’t you just set that as the default? ‘Cause it looked cleaner? I also set it to not float, since that makes it not have the weird popup thingy for new tabs. I love the keyboard shortcuts settings. To be honest that could have been a thing that tipped me to use it, if I wasn’t happy with the default Firefox ones, since that is really handy to have.
Search. Okay, can you tell me why you didn’t set my preferences from earlier? Sure Ecosia is the default search engine, but if I enabled different search engine for private tabs, that would be Google again. Why?
Now we come to my main pain point. You claim to be privacy focused? Then what are these defaults in the privacy and security settings? They are basically stock Firefox, just with removed Mozilla data reporting, which is the bare minimum for me. You don’t enforce HTTPS everywhere and also don’t have DNS over HTTPS set up. Furthermore you have the “Do not track” feature enabled, which is used for fingerprinting, since not many have that enabled. It is really ironic.
Okay, I don’t want to go into indepth detail on the privacy and security here much further. I’ve listed some more points in the table above. There is one last thing that I find curious though: Firefox-Sync isn’t disabled, even though it says on your page you try to remove most of Mozillas tracking features. This thing has metadata it sends and could have been easily deactivated via a config entry.

I used the browser for a bit and told it to not set itself as a default browser. Since I didn’t like it in the end and didn’t want to make it actually private, I deinstalled it. But look at that: Now it is the default option for opening html files? It didn’t delete its desktop files, even when deleting flatpak data.