OpsGenie is an IT notification system that allows developers to send messages to users via email, SMS, phone calls, and mobile push notifications. Unlike some systems, OpsGenie does not limit alert messages to a few simple characters. Alerts can contain free form text, tags, additional fields, and even files. OpsGenie monitors the entire notification system from end to end using "heartbeats", which are analogous to pings. The OpsGenie APIs allow users to manage alerts, users, groups, schedules, heartbeats, and more via REST calls.