iOS Musician Apps (69) Supported Technologies is Audio Unit (AU), Type is Tool

MIDISpy - MIDI Monitor. A handy little utility for monitoring MIDI connectivity.

Metronomics is not only a metronome, but a tool designed to help build a solid sense of time and rhythmic security.  It's a new kind of metronome -- use Metronomics to generate random patterns, sequenced grooves, or a combination of both to help you practice with more than just your typical click track.

"QuantiChord" is a MIDI effect that generates chords from incoming notes and quantizes the results to a pre-defined scale. It can be used as a standalone application or as an Audio Unit MIDI effect plug-in.

AUv3 Midi sequence generator which generates musical evolving sequences  that you can further automate or modulate via midi.

Harmonizr is a vocal harmonizer offering a unique and fun user interface.

Physicles is a container of physics-based Audio Unit MIDI plugins. These AU MIDI plugins generate MIDI messages through the use of an underlying physics engine, which models the physical interactions between various entities.

"StepPolyArp Unit" is a real-time polyphonic and polyrhythmic MIDI step arpeggiator and step sequencer. It can be used as a standalone application or an Audio Unit MIDI effect plug-in.

RouteMIDI, in conjunction with a DAW such as Garageband, will allow you to create tracks that will use any of your external MIDI synthesizers for that track, as alternate to instruments etc. built into the DAW.

midiSTEPs is a powerful and fun MIDI step sequencer app that sends MIDI note and CC messages to other music apps and external synthesizers.