MASM Builder is a free Integrated Development Environment IDE for developing 32-bit Windows programs using the Assembler. MASM Builder contains many useful features which will assist you in creating Windows API based programs.
The Netwide Assembler, NASM, is an 80x86 and x86-64 assembler designed for portability and modularity. It supports a range of object file formats, including Linux and *BSD a.out, ELF, COFF, Mach-O, Microsoft 16-bit OBJ, Win32 and Win64. It will also output plain binary files.
Easy Code is the visual assembly programming environment made to build 32-bit Windows applications. The Easy Code interface, looking like Visual Basic, allows you to program Windows assembler applications (executable files, dynamic and static libreries, COFF object files...