The tech stack is pretty straightforward (Rails back-end, using Expo/React Native for the mobile apps).

The biblical texts are actually rendered in a WebView and the native code communicates back/forth to the WebView with a basic javascript bridge. I wasn't sure this approach would work at first, but it's actually worked out quite nicely.

Handling theological bias has actually been one of the bigger challenges (not technical of course). People have such drastically different views and prejudices of the Bible that I'm always walking a careful line of what resources are approved vs not.