Disassembler

A disassembler is a program which converts executable code into assembly language.

An assembler converts assembly language to machine code. A disassembler reverses this process.

A disassembler can help you to figure out how a program works, which can be the first step in changing how that program works.

Disassemblers

Disassembler	License	Platform(s)
IDA Pro (Interactive Disassembler)	Commercial	Windows
GNU binutils objdump	GPL	Unix, Windows
PEDasm: a Symbolic disassembler for Win32	GPL	Windows
Win32 Program Disassembler	Freeware	Windows, Linux
RosAsm	GPL	ReactOS, Windows
Proview (PVDasm)	Freeware	Windows