PyFCM
Python client for FCM - Firebase Cloud Messaging
...It inherits the reliable and scalable GCM infrastructure, plus new features. GCM users are strongly recommended to upgrade to FCM. Using FCM, you can notify a client app that new email or other data is available to sync. You can send notifications to drive user reengagement and retention. For use cases such as instant messaging, a message can transfer a payload of up to 4KB to a client app.