http://www.native-instruments.com/index.php?id=reaktor5_us

LITERAL:
REAKTOR 5 fuses all audio applications into a single, extremely versatile and powerful tool. Musicians, producers and sound designers are all catered to by the very broad range of instruments and sounds already included. Due to the open engine architecture, the potential for building your own highly individual instruments is endless. Whether you are using the instruments from the library or creating your own, the only limit is your imagination.