Plugin Boutique - Inspirational MIDI effect that makes finding chords and progressions intuitive and fun
Captain Chords - Write chord progressions in your favorite DAW
RapidComposer - MusicDevelopments RapidComposer: Music Prototyping and Automated Composition Software
Cthulhu - VST MIDI-FX plugin for harmonic inspiration
Odesi - ODESI is a music sketchpad that exports your projects to Audio and MIDI.
AudioCipher - AudioCipher is the text-to-midi DAW plugin that transforms words into MIDI melodies and chord progressions.