What are some alternatives?
Splice Beat Maker - Make and share beats in your browser
FL Studio - Image-Line's FL Studio, now on it's 12th version, is a well-known music production suite and the most popular beat processor on the market, due no doubt to its longevity. Read more about FL Studio.
Airdog 2 - All-terrain, camera drone that follows you in action
Pure Data - Pd (aka Pure Data) is a real-time graphical programming environment for audio, video, and graphical...
Google Music Lab - Interactive experiments that use the Web Audio API
Renoise - Renoise is a digital audio workstation.