ejabberd is an Extensible Messaging and Presence Protocol (XMPP) application server and an MQ Telemetry Transport (MQTT) broker, written mainly in the Erlang programming language. It can run under several Unix-like operating systems such as macOS, Linux, FreeBSD, NetBSD, OpenBSD and OpenSolaris. Additionally, ejabberd can run under Microsoft Windows. The name ejabberd stands for Erlang Jabber Daemon (Jabber being a former name for XMPP) and is written in lowercase only, as is common for daemon software.