Since I keep getting asked as to what tools I use to write this and whether fellow coders can contribute or extend the app, I painted a little diagram that hopefully makes things clearer. This is just a very high level diagram of the components.
The maybe most important things here for developers out there are the points (6) and (11). By using the publicly available external REST service, users can create their own apps – these can be mobile apps, web apps or desktop apps (i.e. for Mac or Linux).
But please be patient – it will be many weeks before any API is stable enough to be published.