Google Cloud Messaging (GCM) was a notification service that enabled developers to send messages between servers and client apps running on Android or Chrome. Launched June 27, 2012; shut down May 29, 2019 — it lived 6 years. One of 37 Google products killed in 2019. Google Cloud Messaging (GCM) is a defunct mobile notification service developed by Google that enabled 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 web 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 It has since been superseded by Google's Firebase Cloud Messaging (FCM) on May 29, 2019. Wiki link Data: Killed by Google (killedbygoogle.com, MIT).