Projects / ReactOS


ReactOS is an advanced operating system providing a ground-up implementation of a Microsoft Windows XP/Windows Server 2003-compatible operating system. It aims to achieve complete binary compatibility with both applications and device drivers meant for XP and NT 5.2 operating systems by using a similar architecture and providing a complete and equivalent public interface. Written completely from scratch, ReactOS is not a Linux based system, and shares none of the UNIX architecture.

Operating Systems

Recent releases

  •  22 Aug 2013 11:10

    Release Notes: This release adds preliminary support for USB mice, keyboard, and storage devices, a rewritten session management subsystem, an alternate ReactOS Memory Management Module which has taken over all memory management responsibilities except for sections, AHCI support with an updated UniATA driver, preliminary support for debugging ReactOS components using windbg, improvements based on results from the AutoHotKey application functionality test suite, and bugfixes based on running Driver Verifier on several bundled drivers.

    •  25 Oct 2012 09:40

      Release Notes: CMake and MSVC efforts continue and a variety of linking bugs have been resolved due to differing strictness between GCC and MSVC. Service control manager events are now logged in the system log. Service startup and shutdown has been cleaned up significantly. The pagefile has been limited to 2GB in size due to FAT limitations.

      •  18 Dec 2009 14:40

        Release Notes: A rewrite of the kdcom kernelmode library, which is now much more compatible with the Microsoft version. This allows for improved built-in support for WinDbg. Support for delay loaded DLLs has been added to the build tools, providing delay loading functionality for shipped libraries. Support for Chinese and Korean fonts has been added. A selection of application compatibility improvements can now been seen, including Opera, Open Office, Firefox 3.5, VLC1.1, and Skype. Synchronization of most of the Wine usermode DLLs and some Win32 subsystem code shared with Wine.

        •  29 Apr 2009 12:17

          Release Notes: Various NDIS and AFD problems have been solved, which increases compatibility with third party NIC drivers and hardening of the network stack. Preliminary support was added for sound via the new Kernel Streaming service. It's now possible to use the ac97 driver via the new Port Class library to play sound bytes using winamp. The command prompt is more compatible. Many bugfixes were made to the kernel mode portion of the GDI, resulting in a much improved drawing engine across all bit depths.

          •  05 Feb 2009 22:00

            Release Notes: Various bugfixes and enhancements to kernel core services (e.g. registry, system information routines, sync primitives like guarded mutex, I/O support, and others). An initiative has been started to fix the remaining unstable parts of the kernel: Memory Manager, caching code, and filesystem driver APIs and other dependencies of Mm. Introduction of a new Portable Structured Exception Handling mechanism (PSEH 2.0). Various GDI drawing problems were fixed.

            Recent comments

            08 Dec 2001 08:12 whetphish

            ReactOS Status
            The kernel is getting more and more stable and much of the Win32 GDI has been completed, but there is still a lot to do.

            Work has begun porting WINE from the Linux platform though it can't be completed without a fully functional GDI. If you can offer any help with any part of this project then please visit and subscribe to the mailing list to find out what's going on at present.



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