Stave'n'Tabs - iOS and macOS notation and tablature editor with MIDI and MusicXML files support and chromatic...
Simply Piano - Fast and fun way to learn piano
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!
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Aria Maestosa - Aria Maestosa is an open-source (GPL) midi tracker/editor.
Yousician - Learn to play music at home, at your own pace