Google Cloud Messaging

Google Cloud Messaging (GCM) was a mobile notification service developed by Google that enables third-party application developers to send notification data or information from developer-run servers to applications that target the Google Android Operating System, as well as applications or extensions developed for the Google Chrome internet browser. It was available to developers free of charge. The GCM Service was first announced in June 2012 as a successor to Google's now-defunct Android Cloud to Device Messaging (C2DM) service, citing improvements to authentication and delivery, new API endpoints and messaging parameters, and the removal of limitations on API send-rates and message sizes. It has been superseded by Google's Firebase Cloud Messaging (FCM) on May 29, 2019.