Helio Workstation is free and open-source music sequencer, designed to be used on all major platforms. One music sequencer for all major platforms, both desktop and mobile.
SoundPrism Electro app is a musical instrument for iPad which makes it easy to come up with great chord progressions.
Phase84 is a next generation phase distortion synthesizer music app for iPad. Phase84 fuses gritty digital sounds with traditional analog punch.