Reaktor is a graphical modular software music studio developed by Native Instruments (NI). It lets musicians and sound specialists design and build their own instruments, samplers, effects and sound design tools. It is supplied with many ready-to-use instruments and effects, from emulations of classic synthesizers to futuristic sound design tools. In addition, more than 3000 free instruments can be downloaded from the growing User Library. One of Reaktor's unique selling points is that all of its instruments can be freely examined, customized or taken apart; Reaktor is a tool that effectively encourages reverse engineering. Reaktor Player is a free limited version of the software that allows musicians to play NI-released Reaktor instruments, but not edit or reverse-engineer them.