Follow on Twitter for updates, especially if you are a user of a mobile device of an older Android version: @nd_rue. Judge Core App, the app created with the intention of being the core app for expansion if need be. Supposedly picking up where MTG Judge left off, it has spawned itself into a new project. Runs perfectly fine offline - great for when you're judging overseas.
NDRue Developments is the developer of this application that can be found in the Tools category. Over 50K users installed the app and the most recent update was launched on Oct 14, 2019. Users rated MTG Judge Core App 4.7 on Google Play.