WinAsm Studio is a free integrated development environment (IDE) for developing 32-bit Windows and 16-bit DOS programs using the Microsoft Macro Assembler (MASM). WinAsm Studio is optimized for size and speed, yet contains a number of useful features such as intellisense which will assist you in creating Win32 API based programs. Highly extensible via user-created add-ins. Now with a built-in Visual Resource Editor. WinAsm Studio is a front-end to MASM but does not contain any MASM file. MASM itself can be obtained via Hutch's MASM32 distribution.
