I want to use Firebase Authentication in my mobile app, however I want to host the mobile backend (REST API and database) on Azure. In this case, how would I get the identity information from Firebase over to Azure, e.g. how would I check in my Azure backend if a token sent from my mobile app to the Azure backend is valid, get the name of the logged in user etc?
You can use the Firebase Admin SDK to verify auth ID tokens sent from your app to your backend.