ABOUT THE MOVE TO FIREBASE:
Recently, Google sent out info about the switch to Firebase. This is the current situation:
- All existing apps linked to existing GCM Projects will continue to work just fine. Next year (April 2019), we will have to be ready for the final move to Firebase but we'll handle this move as a High Priority Change. We will be ready!
- The procedure to create new GCM Projects still exists but has changed a lot. This KB-article explains you the new procedure!
Required for sending push notifications on Android.
You can find the new instructions in this KB-article.