List of free emulator stuff for developerππ½
If you're looking for all programming tools around emulator (not just free). Check this page List of emulator Programming Tools

QEMU
QEMU is a generic and open source machine emulator and virtualizer.When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC)
Tag: emulator