Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Bandlab - Capture, nurture, and collaborate on song ideas in the cloud
MMA - “MMA—Musical MIDI Accompaniment” is an accompaniment generator.
Krue - Twitch for music: live streams from amazing musicians
Guitar Pro 7 - Create, play and share your tabs
Soundscape - Sync your music with the open source community