MyBytes is like a trimmed but online version of FruityLoops or Adobe Audition. This service lets you can create MP3 ringtones and original songs inside your web browser without requiring any downloads.
To use MyBytes, open the Music Mixer tab and just drag any number of music loops from the built-in loop browser to the individual tracks.
When you are done composing the original music track, set the usage rights or download the song as an MP3 file.
MyBytes Mixer - It’s a Microsoft sponsored project for the student community but everyone is free to use it.