It is available and mature for development on DOS, OS/2 16 and 32 bit, Windows 3.1, Windows 95/98/Me, Windows NT/2000/XP and later, and has a Linux port that being newer is not quite as fully formed but is getting lots of updates. The system has a full cross platform capability, i.e. the OS/2 version can be used to develop for DOS and MS Windows targets and vice versa.
The system was forked in 2012 after a member of the OpenWatcom team deleted almost all contributions to the system from others than the core team, the bulk of the developers that had been actively working on the system now work on the fork that is informally know as the "Malak" version. The deletions had been an ongoing problem ever since the inception of the project and are the reason why various attempts to update the FORTRAN side of the compiler have disappeared off the face of the earth. Most if not all new development of the Open Watcom code-base now happens on the fork and not on the original version of OpenWatcom.
OS/2 Versions Available
Published under the Open Watcom Public License. Allows free commercial and non-commercial use of Open Watcom.
Open Watcom C/C++ and FORTRAN 77 are open source versions of Sybase Powersoft Watcom Version 11 products.
Initially targeting QNX, but later adding DOS, OS/2 and Microsoft Windows to their target list. While QNX hosted versions of the tools disappeared from the last edition of the commercial version of Watcom, it was still available as a target architecture.