Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Captain Chords - Write chord progressions in your favorite DAW
MMA - “MMA—Musical MIDI Accompaniment” is an accompaniment generator.
RapidComposer - MusicDevelopments RapidComposer: Music Prototyping and Automated Composition Software
Sundog Scale Studio - The MIDI chords and melodies laboratory
Cthulhu - VST MIDI-FX plugin for harmonic inspiration