The backend server runs on node.js, using a REST api framework loopback.js
The web client is programmed in React.js, and is a pure javascript 1-page app for the most part.
The iOS and Android apps are programmed using React Native, using a unified code base.

I am sure there are numerous bugs left in the system, so I hope you can live with them for a little while as I continue to make J-Novel Club better and better!