Stave'n'Tabs - iOS and macOS notation and tablature editor with MIDI and MusicXML files support and chromatic...
Captain Chords - Write chord progressions in your favorite DAW
Aria Maestosa - Aria Maestosa is an open-source (GPL) midi tracker/editor.
RapidComposer - MusicDevelopments RapidComposer: Music Prototyping and Automated Composition Software
Chordsheet Maker - Create chord sheets or lead sheets quick and easily from your iPad. Add rhythms, endings, segno, codas and all what's necessary for your musicians to know what's your music about. Transcription made easy!
Cthulhu - VST MIDI-FX plugin for harmonic inspiration