Zen Browser: An Open-Source Alternative to Arc

I’ve been a Firefox user for a long time (since version 1.5). I still use Firefox every day.

Last year I tried Arc for couple of weeks.

What I liked about Arc is its approach to browser design. Spaces really help you separate your work streams, and the nature of vertical tabs helps with many tabs when doing research. If I was a Chrome user this is probably the browser I would’ve picked. However, Arc is not without its issues:

• Firebase security incident from 2024 CVE-2024-45489
• Browser company focusing on other projects
• It’s closed source

I haven’t really seen a browser that makes browsing as easy. That is until I stumbled on Zen browser. And Zen browser is gorgeous.

• It’s open sourced based on Firefox. Even better, it works with Firefox Sync so you can get all your bookmarks and settings.
• It sees rapid development with the developer pushing updated every 1 or 2 weeks.
• You are always on the latest Firefox version, so you don’t really miss anything on vanilla features by using a fork.
• It has its own extensions on top of the Firefox extensions that give you further customization.

Is it as polished as Arc? No, it isn’t. But it compensates that with an active community, open source nature, and being a browser not based on Chromium. Ok, the last one might not really count as a benefit, but it will be a sad world if we end up with only one browser engine.

My Setup

I primarily use Mac for my daily work, so while most of these steps apply to all operating systems, some Mac-specific options are noted where relevant.

1. Sync with Firefox Account

After downloading Zen, first thing I did was login to Firefox Sync and get all my extensions and bookmarks. There’s nothing different here from what you’d do on a regular Firefox installation.

2. Show a full width address bar and extensions

Having that done and out of the way I went into the Settings. I still prefer my address bar to be full width.

This also allows me to add extensions in the top bar.

3. Install Zen extensions

Zen provides its own extensions. They change the way things look or add additional functionality. You can access them by going to Settings → Zen Mods or by visiting https://zen-browser.app/mods/

Here are the ones I’m using:

• Better Unloaded Tabs
  Makes unloaded tabs easier to notice by making them greyscale and transparent.
• Only Close On Hover
  Show tab’s close button only on hover, even on the active tab.
• Private Mode Highlighting
  Adds extra theming and an icon to the main toolbar of any private browsing window.
• Quietify
  Adds a visualizer animation to the mute button on tabs.

4. Adjust Opacity on Mac OS

One thing I don’t like is the default UI opacity. Fortunately that’s configurable.

• Open about:config
• Search for zen.widget.macos.window-material
• Allowed value is from 1 to 7, with higher values being more opaque. I prefer to set it to 6. This gives me enough transparency without being distracting.

5. Bookmarks toolbar menus vertical spacing

The spacing in the dropdown menu Zen has by default is a little too big for my taste. I prefer menus a bit more compact so there’s no vertical spacing.

Since I didn’t find an extension or setting to change this, I made the necessary changes using userConfig.css (userChrome explained)

1. Go to Help → More Troubleshooting Information
2. Find the role for Profile Folder and click on Show
3. From the OS File Explorer that will open navigate inside the chrome folder
4. If there’s no userChrome.css file create a new empty file with that name
5. Paste the code for reducing spacing and save the changes.

/* Reduce the gap in the dropdown menu */
menupopup > menuitem,
menupopup > menu {
  margin-top: 0 !important;
  margin-bottom: 0 !important;
  padding-right: .5rem !important;
}

Restart Zen open any root level folder from the bookmarks toolbar.

6. Mobile browsing

Zen doesn’t have a mobile version, and you don’t really need one. Since it works with Firefox Sync, you can have Firefox mobile installed and still get all the bookmarks and anything else you sync from Zen.

7. Netflix, HBO, Disney+ and DRM

Zen Browser lacks DRM-support. If you open Netflix or any other major streaming platform videos won’t work. The reason is explained in the FAQ and it’s not something that can be easily solved at this point.

Note that this doesn’t affect YouTube.

The additional quality of life improvements Zen provides compensate this. What I’m doing is whenever I want to watch Netflix or HBO Max is open Firefox.

So-o-o, yes you might have to keep Firefox installed, even for the sake of being able to play DRM content.

8. External Password Managers (1Password)

Password managers like 1Password might not recognize Zen out of the box. There’s an easy solution. In 1Password desktop app open Settings and navigate to the Browser tab.

You’ll see a section named Connect to additional browser. Add Zen there.

Features

• Vertical tabs and workspaces
• Essential tabs at the top staying across workspaces
• Flexible toolbar and sidebar customization matching Firefox’s native options
• Tabs split view. Shift or cmd and select more than one tab, then right click and select Split N Tabs
• Inactive tabs unload after 40 min with a visual indicator which tabs are in memory and which one aren’t (Zen Extension)
• Media player controller integrated with Picture-in-Picture
• Pinned or floating side panel. Really convenient for Google Translate, Wikipedia and news websites