g4exa is a (quite simple) Geant4 application that uses the inlib/exlib tools to do its user interface and graphics. It is intented to be a template application for people wanting to use these tools to write their own Geant4 application, in particular to run on Android and iOS devices. The code is based over the Geant4 A01 example, the Geant4 core and the inlib/exlib tools. The "how it is done" is similar to the one of the ioda application.