ReactOS: Open source Windows

Oct 20, 2008
Updated • Mar 11, 2013

Windows is a proprietary operating system which you cannot compile or modify at a source code level. This allows Microsoft to maintain control of their operating system and many people disagree with the notion of using closed source software.

ReactOS is a free and open-source operating system, which has been in the alpha stage of development for about 10 years, which allows Windows applications and libraries to be executed without having to use a single piece of Microsoft-owned code!

A similar project to ReactOS is WINE, which allows you to execute Windows binaries in Linux and OS X.

ReactOS has an easy-to-use graphical interface, which resembles Windows Classic. Some things, like the Windows logo, are avoided however. It adds some features Windows lacks by default, such as virtual desktops.

The practical uses of ReactOS are somewhat limited. The operating system can run many Win32 applications, but this is patchy, and support for .NET Framework applications, OpenGL and DirectX is still being developed. Their own website acknowledges that ReactOS is 'not recommended for everyday use'.

Their website boasts a selection of screenshots of all sort of programs running under ReactOS, for example, Mozilla Firefox, VB5, Winamp, Diablo 2 and Unreal Tournament!

ReactOS with a classic Windows game!
ReactOS with a classic Windows game!

The operating system is probably not usable as of yet as someone's main operating system, but its idea and sheer curiosity value makes it fascinating. When it becomes stable, it will be interesting to see how a completely Win32-compatible operating system fares against Windows XP and Windows Vista.

The project maintains a compatibility database that you can use to find out if a program that you are using is supported by the operating system yet. It currently lists less than 1000 applications and drivers which may not sound like a lot but features prominent programs such as Firefox, Cpu-Z or Nvidia display drivers.


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  1. Cisco&Linux said on July 22, 2011 at 3:37 am

    i think linux will be allways be the Best free OS

  2. patachu said on March 17, 2010 at 3:10 am

    My bets remains on this project, and of course its developement takes time: it aint like rewriting an unix but a working windows clone. Also that project lacks support from the open community, focused on their linux/bsd. That’s’not how you fight microsoft. On the hpc/server market maybe linux has a place, but not in homes and offices yet.
    Know your enemy.

  3. Sameer said on March 30, 2009 at 8:58 pm

    @Brian : i think i will have to agree with you ;)

  4. Brian said on March 30, 2009 at 7:35 pm

    Yeah, but then it’s best to go to a Linux server rather than an alpha version of some project software. I would bet that anything that will run on the current version of ReactOS will run seamlessly on Wine (which ReactOS is affiliated with).

  5. Sameer said on March 30, 2009 at 2:06 pm

    ReactOS may be buggy and not very advanced but it can be a really nice alternative to windows in a corporate environment or somewhere people don’t need to use extensive windows functions and just run a webserver or omething

  6. ct2193 said on February 19, 2009 at 6:53 pm

    Hmm… ReactOS is still sketchy and not all that stable… Not recommended for practical use yet…

    Sounds like they’re right on track for simulating a real installation of Windows. I suppose they’ll have to bloat their code before they’re near identical.

    Of course I only joke about this because of all the unstable systems I’ve dealt with over the years – I do think XP Pro was one of the best systems MS put out and now they’re abandoning it for Vista & Win 7 which suck like Windows ME.

  7. some1 said on November 8, 2008 at 8:50 pm

    @Brian: Hey , Its still alpha…
    The release cycle is about 2 months , not 6.
    Next ahead among other things is usb support!! ;)
    The release build includes “Downloader” which installs Firefox 1.5 or Firefox 2 and they works ok.

  8. Joe said on October 24, 2008 at 10:17 pm

    @DjFlush: I wrote that, not Martin! Also, I think it is ‘free’. Any files which were unfree have been audited for.

    ‘The ReactOS Project releases almost all of its code under the GNU General Public License ( Each developer maintains his or her copyright in the developed source code, but licenses that code under the GPL for use by the ReactOS Project.

    Some portions of ReactOS may be licensed under other licenses, including the GNU Lesser GPL, or placed into the public domain. This is generally done only when necessary for compatibility with other projects. ‘

  9. Avatar said on October 24, 2008 at 8:25 am

    Linux-XP from Russia must be the Linux Distro that got the closest to its goal of replicating Windows. it was quite remarkable. i wonder what happened to that project?.

  10. DjFlush said on October 21, 2008 at 8:08 pm

    Nice find Martin! after doing a little research I found that it is a free operating system but still not open source.

  11. Dotan Cohen said on October 21, 2008 at 9:59 am

    While ReactOS is interesting, I must stress that has very little usage as a real OS. I may soon install it on an old library computer that must run some Win98 application if I cannot get it to run in wine on Xubuntu, but then again if Wine fails to run that binary, then I do not have much hope for ReactOS. I fear for Wine’s terrible implementation of Hebrew (RTL) support, whereas the ReactOS team may have taken a different route.

  12. doit said on October 21, 2008 at 7:55 am

    Well, nothing that much compared to this –

  13. Brian said on October 20, 2008 at 11:53 pm

    I’ve been following this for a couple of years now, and the progress is SLOW. They release minor version updates (0.34–>0.35) every three to six months, and it won’t hit the Beta phase until it gets to version 0.5. that’ll be another two years at this rate. currently, the interface defaults to a “feel” that’s somewhere between Windows 3.11 and Win95, even though it has kernel compatibility with Win32 apps. And, man is it buggy. The LiveCD builds won’t boot on every computer, and have almost nothing to test drive within them. The VM won’t install a web browser to test even the lowliest functions. it will install AbiWord, and that actually looks fairly nice. but it’s slow.

    I’m not knocking the effort, because I like the idea of a free (or at least cheaper) version of Windows. Kinda like I rooted for AMD and Cyrix when they were heavily competing for Intel’s throne. Only Cyrix dropped out of the running early on. And I fear that’s what’ll happen to ReactOS.

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