Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
CKEditor - Real-time collaborative future-ready rich text editor
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.
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.
Quill - Powerful, API-driven rich text editor