WaveBots Editor - Procedural music and sound maker that exports to Wav, MIDI, GoatTracker and much more.
Abundant Music - Generate royalty free music with a simple but very powerful procedural music creator
AIVA - The AI composing emotional soundtrack music
Tape It - App for songwriting & audio recording.
WolframTones - Listen to what I just found in the WolframTones music universe
RiffShare - Write down a musical riff, send to band members, collaborate