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.
Notation Pad - Notation Pad is the Easiest way to write sheet music with notations on iOS/Android.
Guitar Pro 7 - Create, play and share your tabs
Orpheus App - Sheet Music Reader for Android
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.
LilyPond - GNU LilyPond is a computer program for music engraving.