When we talk about Windows app compatibilty, we usually think of Linux running some sort of WINE configuration. That’s not all the wonderful world of open-source has to offer though. Some really talented developers have managed to reverse engineer the Windows NT architecture. They’ve been working on it for almost 30 years. The project is called ReactOS, and it’s directly compatible with Windows software and drivers (no compatibility layers or emulation required).
What is ReactOS?
ReactOS is a free and open-source operating system that natively supports Windows apps and Windows drivers. When you download a .exe file on ReactOS, you can just double-click, and it’ll run the installer just like it does on regular Windows. No WINE trickery required.
It mimics the Windows NT kernel, so (at least in theory) you can even install the legacy hardware drivers meant for old Windows systems. Basically, those old devices would treat ReactOS as an actual Windows machine.
How is it even possible to replicate a closed-source kernel and operating system? That’s what makes this project so wildly impressive. From what I read in the documentation, the devs are reverse-engineering the Windows OS in a legal way. They run commands on actual Windows systems and create technical specs of how those commands and components behave. Then they write code based on those specs, recreating the Windows design without ever looking at its source code.
Installing and booting into the OS
ReactOS is incredibly lightweight. The installer image barely weighs 200MB and installing it took less than a minute. Instead of a fancy point-and-click installer, you get an entirely text-based interface. You’re supposed to interact with it using a keyboard to format the storage drive and run the installation.
The installation took about a minute. Then the machine booted into ReactOS and walked me through a quick setup. That took another minute. I recently had to reinstall Windows 11 and it took almost an hour. I had to connect to the internet, sign up for a Microsoft account, and solve CAPTCHAs. ReactOS also booted really fast. So far, so good.
A blast from the past
If you’re old enough to have seen or used Windows 95 or Windows XP, the ReactOS interface feels eerily familiar. Right-clicking on the desktop reveals an almost identical context menu. Click on “Properties” and you’ll find an old-school wallpaper and screensaver menu. There’s an Explorer with a C: drive and everything. There’s a taskbar and a start menu that mimics the XP style.
Evidently, it’s pretty bare bones and lightweight compared to modern Windows. There is also a software store, where you can find all kinds of freeware games and applications. I’m sure you’ll recognize at least some of them.
It has its own Internet Explorer
There’s even a clone of Internet Explorer preinstalled on this OS. True to form, it doesn’t work. It looks ancient and can’t load anything, just like the real thing. Even Google search isn’t supported.
I tried looking for a browser in the software center. I found a browser called K-Meleon. Sadly, K-Meleon couldn’t load HTTPS either. Firefox, unsurprisingly, did work. There’s a special version of Firefox called Firefox ESR (or Extended Support Release) that’s designed for old computers. It loads the How-to Geek website just fine. Its YouTube performance wasn’t great. It does fine for lightweight browsing though.
It’s much more than just a theme
It doesn’t just look like Windows, it actually works like Windows too. Most alternative operating systems that I’ve found are Unix-based or Unix-like, where everything is a file. Windows is more object-oriented and treats everything as a structured object. That’s what ReactOS does too.
It uses the same kind of file system (it even has partial NTFS support.) You’ll notice that ReactOS itself is installed in a C: drive. The OS has replicated all the kernel components, runtime environment, and DLLs that a Windows program expects.
That’s why you can just double-click on a .exe file and install it directly onto the machine without any translation layers like WINE. The program will be able to talk directly with Windows drivers too. Although the project’s README does state that it shares some code with the WINE project to provide that native environment.
There’s even a registry key system that looks almost identical to the one we have on Windows. There’s a Task Manager that shows familiar processes running in the background.
I’ve never installed Windows apps like this
If you’ve ever tried running Windows apps on a non-Windows operating system, they either run inside an emulator (a virtual Windows computer) or they translate Windows commands into Linux commands by using a compatibility layer in the middle (like WINE.) Since they’re not running on bare metal, these methods have an overhead or extra work that the computer has to do. It’s why Windows apps running on alternative operating systems feel so much slower.
On ReactOS, there is zero overhead because the apps “think” they’re running on Windows. There are caveats though.
So does it beat Windows?
Not even close. First, ReactOS is in the alpha stage of development, and it has been for the last three decades. You can’t just install it on a modern computer and expect it to run normally. It’s not stable enough for daily use yet, and you’ll be frequently running into errors. Even if you ignore the errors, ReactOS is 32-bit, so you’re limited to 4GB of RAM, and it hasn’t implemented multicore CPU support yet. There’s no GPU acceleration either.
As an enthusiast, I can appreciate that this open-source Windows is a technical marvel, but ReactOS is not going to replace your Windows system. So far, Linux remains the best alternative for people trying to ditch Windows.
