Flowkey - The easiest way to learn piano with your iPhone or iPad
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.
Jameasy for Violin - Play rhythm game with a real violin. you can play with background music and real-time feedback
Guitar Pro 7 - Create, play and share your tabs
alphaTab - alphaTab is a cross platform music notation and guitar tablature rendering library.
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.