There are quite a lot of people squatting on rpsls-related domains, sadly.

The app's 100% JavaScript, served from a static server, and backed by Firebase. https://www.firebase.com/ You include their library and create a reference to any point in your "Firebase", which is essentially a live JSON store that each client subscribes to. Clients can push data to the store and declare callbacks that fire when data changes at any given endpoint. Changes persist in near-realtime between all connected clients. It is very neat.