Abundant Music - Generate royalty free music with a simple but very powerful procedural music creator
NtEd - Music Score Notation editor.
AIVA - The AI composing emotional soundtrack music
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
WolframTones - Listen to what I just found in the WolframTones music universe
DaCapo Editor - DaCapo Editor is a free Open Source music sheet editor which allows to easily create nice looking partitions. It is available as a web application as well as a desktop application for Windows, MacOS and Linux.