NASM, the Netwide Assembler
The Netwide Assembler has been around for over 2 decades. And it keeps up with the times, releasing new versions every now and then. It's free, open-source and has a complete documentation updated along with each new release.
One of the most convenient tool for fans of the Assembly language, even for beginners.
It's instructions set (similar to those in the Intel Software Developer Manual) and the the syntax at base are easy to grasp.
The community is pretty active, too, and happy to help those getting stuck (and if you dare to try working at this level, expect it to happen very often).
- Targeted for Intel x86 / x64 platforms
- Supported output formats: a.out, ELF, COFF, Mach-O, 16-bit and 32-bit OBJ (OMF) format, Win32 and Win64
- It can also output plain binary files