Lucas0623z / NoteLite

Open-source desktop app that recognizes sheet music from PDFs or images into editable scores, then exports MusicXML/MIDI and offers guided practice.

helge17 / tuxguitar

Open source guitar tablature editor

git-moss / DrivenByMoss

Bitwig Studio extensions for many controllers: Ableton Push I/II, Akai APC40mkI/mkII/mini, Fire, Arturia Beatstep, Novation Launchpads / Remote SLs, NI Maschine / Komplete, Open Sound Control (OSC) and many more.