Mattermost - Mattermost is an open source alternative to Slack.
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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.
Slack - A messaging app for teams who see through the Earth!
MuseScore - Our goal is to let musicians from all over the world create and share their works, as well as to make learning music exciting, easy and available for all.