Maintain and enhance the Watcom C, C++, and Fortran cross compilers and too

Open Watcom C/C++
Free
Offline
http://www.openwatcom.com/index.php/Main_Page

Open Watcom is a project of the open source community to maintain and enhance the Watcom C, C++, and Fortran cross compilers and tools. An Open Source license from Sybase allows free commercial and non-commercial use of Open Watcom. More about Open Watcom's features. Details about Open Watcom's history. Work in progress includes numerous Unix ports (Linux, FreeBSD, Solaris, OS X), support for new processors (AMD64, ARMv7), support for new language features and standards, a C++ STL implementation and more. Join the fun!