GridSound
(development/unstable)(GNU Affero General Public License v3.0)(web)
GridSound is a work-in-progress open-source digital audio workstation developed with HTML5 and more precisely with the new Web Audio API.
You can use the application directly on gridsound.com/daw it’s also possible to create an online account here gridsound.com to save your compositions online and share them with friends.
Give it a try!