ReactOS has reached a notable milestone, as today, January 22, 2026, the project marked 30 years since its first commit. But before we continue, let me briefly explain what this operating system actually is, since it often stays out of the spotlight compared to Linux, which tends to take center stage here.
ReactOS is a long-running open-source operating system project that aims to re-implement the Windows NT architecture from scratch, allowing Windows applications and drivers to run natively without Microsoft’s code.
But rather than emulating Windows or relying on compatibility layers, ReactOS focuses on binary compatibility at the system level, recreating core components such as the kernel, drivers, and system libraries through clean-room development.
Its goal is simple: to provide a free, transparent, and community-driven alternative to Windows that behaves like Windows where it matters, while remaining fully open source and independent of Microsoft’s proprietary ecosystem.
Now, let’s recall a bit of history. The first major milestone arrived in February 2003, with the release of ReactOS 0.1. It was the first version capable of booting from a CD, though it remained command-line-only and offered no graphical desktop.
Next, between 2003 and 2006, the 0.2.x series brought faster progress. A basic desktop environment emerged with improved system stability. Unfortunately, in early 2006, concerns over potential exposure to leaked Windows source code prompted a comprehensive intellectual property audit and a temporary freeze on contributions, slowing momentum considerably.
Development resumed with the long-running 0.3.x series, spanning roughly a decade. During this period, the project began work on x86-64 support, gained SATA compatibility through the UniATA driver, and added features such as MSVC build support and visual styles.
And so we come to ReactOS 0.4.x series, released in February 2016, which introduced a more Windows-like graphical shell and improved compatibility with standard Windows debugging tools. Today, the 64-bit port largely matches its 32-bit counterpart in functionality, though the absence of WoW64 limits its ability to run 32-bit applications on x86-64 systems. The current version is ReactOS 0.4.15.
Finally, the project’s future plans include ongoing efforts to modernize the build environment, add new NTFS and ATA drivers, support multi-processor systems, enable class 3 UEFI compatibility, enable address space layout randomization, and work toward supporting modern GPU drivers based on WDDM.
What can I say in conclusion, except that after 30 years, ReactOS remains one of open source’s most ambitious operating system projects, still pursuing its original goal: running Windows software in an open environment users can trust. Happy birthday, ReactOS! Here’s to the next 30 years.
