Meet ReactOS: The 30-Year Quest to Build an Open-Source Windows
Have you ever wondered if there is an operating system out there that can run your favorite Windows apps, but isn’t actually made by Microsoft?
Enter ReactOS.
It is completely free, open-source, and has been in active development for three decades. In this post, we will take a simple, hands-on look at what ReactOS is, how to set it up, and how it actually performs.
What is ReactOS? (Spoiler: It’s Not Linux!)
Many alternative operating systems you hear about today are built on top of Linux or Unix. ReactOS is entirely different.
Instead of using a Linux base, the developers wrote a custom Windows NT-compatible kernel from scratch.
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The Goal: To create a lightweight operating system that is fully compatible with applications and drivers written for Windows (ranging from Windows XP and Server 2003 all the way up to Windows Vista and 7).
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Is it legal? Yes! Every line of ReactOS code has been written from scratch by developers to ensure it is completely legal and open-source, though it does leverage some elements from the famous Wine project to help run Windows applications.
Setting Up ReactOS: Nightly Builds & Virtual Machines
If you want to test the absolute latest features (including newer compatibility updates for Windows Vista and 7 applications), you can grab a Nightly Build directly from the official website, reactos.org.
Here are some quick setup details to keep in mind:
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Tiny Footprint: The Boot CD zip file is incredibly small—only about 100 megabytes! Once unzipped, you get a standard ISO file.
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Hardware vs. VM: While you can install ReactOS on physical hardware, it is generally not compatible with modern computers. For the best safety and ease of use, running it in a virtual machine (like VirtualBox) is highly recommended.
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VM Configuration: You can configure your VM to use around 8 GB of RAM, 4 CPU cores, and a 50 GB hard drive to give it plenty of breathing room.
The Installation Experience
Once you boot into the ReactOS installer, the interface will immediately trigger a wave of nostalgia. It looks and feels just like the Windows XP setup wizards of the early 2000s.
During setup, you will encounter a few interesting modern twists:
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File System Choice: Along with the older FAT and FAT32 formats, ReactOS surprisingly supports BTRFS—a highly modern and efficient file system usually found in Linux environments.
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Visual Customization: You can choose from several themes during setup. Choosing a theme like "Mizu" gives it a clean, slightly modernized classic look.
Once the setup completes, you are greeted by a fully functional classic desktop, complete with a Start Menu, Taskbar, Control Panel, and even a familiar-looking Task Manager!
What Works? (And What Doesn't)
ReactOS is still officially in its Alpha stage, meaning it is under heavy development and is not feature-complete. Testing it inside a virtual machine yields mixed results.
The Successes:
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Screen Resolution: You can easily slide the resolution up to a crisp 1080p in the display settings.
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Web Browsing: The built-in "Wine Internet Explorer" works for basic web searches (powered by DuckDuckGo) and loading simpler web pages.
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The Application Manager: ReactOS comes with its own built-in App Manager, allowing you to download popular programs in one click.
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App Compatibility: Lightweight utilities like 7-Zip and even premium legacy Windows tools like Internet Download Manager (IDM) install and launch without a hitch.
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Lightweight Games: Simple, non-3D games like Balloon Fight run smoothly. (crashed)
The Hurdles:
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Clunky Virtualization: Moving windows around inside a virtual machine can feel a bit laggy and sluggish.
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Modern Web Woes: Trying to load heavy modern websites (like the Google Chrome download page) can cause the built-in browser to break or render pages incorrectly.
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System Freezes: Trying to install older web browsers like Chrome 49 or Chromium XP, or launching 3D games like Death Rally, can easily freeze or crash the entire operating system.
The Verdict: A Technical Marvel in Progress
ReactOS is a fascinating piece of software history. The fact that an independent team has spent 30 years recreating the incredibly complex architecture of Windows is nothing short of impressive.
While it is not yet ready to replace your daily operating system—and can be quite unstable when virtualized—it remains an incredibly fun, nostalgic, and deeply educational project to experiment with.
Have you ever tried running ReactOS, or do you have an old PC in your closet that might be perfect for it? Let us know your thoughts in the comments below!
I’ve also made a video on this topic — you can watch it below.
Check out my other posts, I post useful tutorials and tech tips, maybe you will find something useful 😉.