Helio Workstation - Cross-platform lightweight speed-painting tool for creating music.
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
NtEd - Music Score Notation editor.
Guitar Pro 7 - Create, play and share your tabs
MMA - “MMA—Musical MIDI Accompaniment” is an accompaniment generator.
Sundog Scale Studio - The MIDI chords and melodies laboratory