Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.

ChordIQ - Learn notes, chords, sight reading, perfect pitch and more.

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.

soundrop - Soundrop is an app that allows you to create your own personalized sound track to keep you focused or relax.

Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.

muted.io - A magical collection of interactive music theory tools & visual reference pages for musicians and music producers