Mu is an webapp platform which allows developers to build and release webapps from within the browser. Mu has built-in User Authentication, Database Storage and Crypto Payments using BTC.
Mu applications are just plain old HTML, CSS and JS. This gives you the freedom to write whatever you like, whether thats a single page app or just a one file mega app, it's up to you.
Mu's goal is to make it easy for people to develop small apps and ideas without the need for huge infustructure.