EstyJS is an emulator for the Atari ST, written in 100% pure JavaScript, originally developed by Darren Coles. Since 2024 and the release of EstyJS 2.0, the project is maintained by Kai Eckert. The source code is available on GitHub.
Hatari Alternatives
Hatari is described as 'Atari ST/STE/TT/Falcon emulator for GNU/Linux, BSD, Mac OS X, Windows and other systems which are supported by the SDL library' and is a Game Emulator in the gaming software category. There are more than 10 alternatives to Hatari for a variety of platforms, including Mac, Windows, Linux, Web-based and BSD apps. The best Hatari alternative is CLK, which is both free and Open Source. Other great apps like Hatari are PCE, Stella, ProSystem and Z26.