Metronaut - An app to help you play classical music
MuseScore.org - Create, play back and print beautiful sheet music with free and easy to use music notation software MuseScore. For Windows, Mac and Linux.
Violin by Trala - Violin by Trala is a music learning app that is designed specifically for Violin users.
Guitar Pro 7 - Create, play and share your tabs
Simply Piano - Fast and fun way to learn piano
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.