Steem Engine
- A freeware emulator for Linux/i486 and Windows.
- http://steem.atari.st/

NoSTalgia and PowerST
- Features NoSTalgia an emulator for MacOS X (older version for CarbonLib and MacOS 9 available) and PowerST a suspended emulator for MacOS 8/9.
- http://users.skynet.be/sky39147/

Castaway
- An open source SDL using emulator for Linux and Windows/Cygwin.
- http://sourceforge.net/projects/castaway/

WinSTon
- Source code of a not anymore available windows emulator.
- http://sourceforge.net/projects/winston/

Hatari
- An open source emulator for Linux, Mac OS X, and Windows using the SDL library.
- http://hatari.sourceforge.net/

FAST
- A freeware emulator for DOS.
- http://fast.emuunlim.com/

STonX
- An open source emulator for Unix/X.
- http://stonx.sourceforge.net/

The Little Green Desktop
- The largest Atari ST/Emulation Resource on the Internet.
- http://www.atari.st/

Atari ST Emulator Written in Java
- Atari ST emulator written with the objective to make it possible use an Atari ST in a web browser.
- http://www.atari-st.lovely.net/