GNU binutils has objdump, which should work:
-d
--disassemble
Display the assembler mnemonics for the machine instructions from objfile. This option only disassembles those sections which are expected to contain instructions.
-D
--disassemble-all
Like -d, but disassemble the contents of all sections, not just those expected to contain instructions. If the target is an ARM architecture this switch also has the effect of forcing the disassembler to decode pieces of data found in code sections as if they were instructions.
It will already be installed on most Linux distributions that have GCC or other development tools installed, and Windows versions are available via e.g. Cygwin.