Snes9x is an SNES emulator written in C++ with official ports for GNU/Linux, Microsoft Windows, Mac OS X, iOS, PSP, and Android. Development of Snes9x began in July 1997 when Snes96's Gary Henderson and Snes97's Jerremy Koot merged their respective emulators to create Snes9x. Since then, Snes9x has been unofficially ported to more platforms than any other emulator. The emulator is Free software since it is a violation of the license to sell Snes9x. It is still being actively developed despite the departure of its original developers. Snes9x was among the first to emulate most SNES enhancement chips at some level. It was also the first SNES emulator to offer sound output. The emulator PocketSNES for Pocket PCs is based on Snes9X. Although the source code of Snes9x is publicly available, the Snes9x license prohibits its commercial use. In 2005, Retro Gamer called Snes9x "the best SNES emulator available".