JWasm is a free MASM-compatible assembler with these features:
* native support for output formats Intel OMF, MS Coff (32- and 64-bit), Elf (32-and 64-bit), Bin and DOS MZ.
* precompiled JWasm binaries are available for DOS, Windows and Linux. For OS/2 and FreeBSD, makefiles are supplied.
* Instructions up to SSE4.2 are supported.
* JWasm is written in C. The source is portable and has successfully been tested with Open Watcom, MS VC, GCC and more.
* As far as programming for Windows is concerned, JWasm can be used with both Win32Inc and Masm32. Since v2.01, it will also work with Sven B. Schreiber's ancient WALK32.
* C header files can be converted to include files for JWasm with h2incX.
* JWasm's source code is released under the Sybase Open Watcom Public License, which allows free commercial and non-commercial use.