My 5 favorite open source operating systems that aren't Linux

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ZDNET’s key takeaways

• Although Linux is the king of open-source OSes, there are options.
• Here you’ll find a few open-source OSes to toy around with.
• Don’t expect any of these to be viable options for daily use.

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When you think of open-source operating systems, most likely only one option springs to mind: Linux.

That makes perfect sense, given that Linux is the most popular open-source OS on the planet (and starting to catch up with non-open-source OSs). 

Also: Ready for a Linux laptop? I recommend a Tuxedo to beginners and pro users alike

But Linux isn’t the only open-source game in town. In fact, there are several open-source options that you can try. I found five in particular that are interesting enough to share with you, including four that reimagine an operating system from the past and one built by a single developer (take that, Linus).

Let’s see what there is to see within the realm of non-Linux open-source operating systems.

1. Haiku

The first time I tried

Haiku was two-thousand-two

It was in alpha.

Decades later, Haiku has finally reached beta. Yup, that’s one slow development process. What attracted me to Haiku was its slight resemblance to the Afterstep Window manager that I once used and loved. Why the resemblance? Haiku is a reimagining of the late BeOS, inspired by NeXTSTEP (which in turn inspired AfterStep). 

Besides the nifty UI, the craziest thing about Haiku is that it installs in seconds. On top of that, you probably won’t find an OS where the apps run as fast as they do on Haiku. The trade-off is that you might not find the app you need. The good news is that there’s the Haiku Depot, where you can install plenty of apps (even the likes of LibreOffice). 

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Another cool feature found in Haiku is the Deskbar, which gives you quick access to minimized applications and system tray items.

I wouldn’t recommend Haiku for daily use, but it’s certainly fun to play with.

2. BSD

BSD stands for Berkeley Software Distribution and is the closest thing to Unix that you can use on the desktop. Created at UC Berkeley by the Computer Systems Research Group and began as a derivative of the original AT&T UNIX that was created at Bell Labs.

Also: After decades on Linux, FreeBSD finally gave me a reason to switch operating systems

BSD lives on in several derivatives, such as FreeBSD, GhostBSD, MidnightBSD, OpenBSD, NetBSD, DragonFly BSD, and more. At first blush, you might think that whatever BSD you opt to use is actually Linux, because it probably uses one of the many Linux desktops, such as FreeBSD with KDE Plasma. 

I’ve toyed around with several of the BSDs, and one of the most important things I always come away with is how remarkably stable they are. This should come as no surprise, given that BSD was based on an operating system used on mainframe computers worldwide.

The good news is that the BSDs are suitable for everyday desktop computing. In fact, if you want the single most reliable and stable operating system on the planet, try FreeBSD or OpenBSD.

3. ReactOS

ReactOS is what Windows would look like if it were open source and stuck with the Windows XP/7 UI. Although ReactOS isn’t Windows, it does aim for Windows compatibility. You can even choose between a slightly more modern UI or the classic Windows (95/98) option. It allows you to join Workgroups and even install Windows apps.

The installation of ReactOS even resembles that of Windows (though it doesn’t take nearly as long). There’s a version of Internet Explorer you can use, too. 

Also: I saw the ‘MacBook Pro for Linux users’ for the first time, and it’s a legit Windows threat

Although ReactOS looks and feels like Windows, don’t expect it to have all the same features, as this OS suffers from a very slow development process. Also, keep in mind that you’re using an OS based on another, older OS, so there are certain features you won’t find here (such as a universal search bar in the browser). It’s also prone to not working as expected.

Regardless, ReactOS is a fun experiment to try.

4. AROS

AROS is a recursive acronym that stands for AROS Research Operating System. This particular OS is a reimaging of the Amiga OS, a single-user OS that saw its final release in 2025 — 40 years after its initial release. AROS is a full GUI OS with preinstalled apps, including the OWB web browser. 

Although AROS looks pretty user-friendly, don’t be fooled — it’s not. This should be considered a novelty or something of a research project. Installing AROS is a bit tricky because it’s different from other installs, and it doesn’t provide much help.

Also: Why Zorin OS 18.1 is simply the best Linux distro – for anyone

Once you get AROS installed, you’ll find that it’s also a single-user operating system, meaning you don’t log in. When you boot AROS, it goes directly (and quickly) to the desktop, where you can start opening the preinstalled applications and seeing what’s what. Do be warned, you’ll see a lot of application errors and apps that simply won’t open.

Maybe someday, AROS will be a viable option.

5. TempleOS

I place TempleOS on this list for one reason and one reason only — it was created by a single person. Imagine that: A single person is writing an entire operating system alone. Although Linus Torvalds started writing Linux on his own, he wound up with plenty of help along the way. 

Also: Can this $70 Linux app make up for the lack of Photoshop? I tried it to find out

Now, TempleOS isn’t an operating system that you would actually use. In fact, after installation (which takes seconds), you boot into what looks like a text-based file manager. Believe it or not, this is actually a GUI desktop, where you can access your personal menu and open apps like games.

One thing to keep in mind is that TempleOS is very much a biblical-themed OS, and it should really only be considered for a one-time experience and then walked away from. But given that a single person created this OS, it’s impressive.