# EMQ X Broker
EMQ X (Erlang/Enterprise/Elastic MQTT Broker) is an open source IoT MQTT message broker based on the Erlang/OTP platform. Erlang/OTP is an excellent Soft-Realtime, Low-Latency and Distributed development platform. MQTT is a lightweight message exchange protocol using publish-subscribe pattern.
EMQ X is designed for massive clients access and realizes fast and low-latency message routing between massive physical network devices:
- Stable to host large-scale MQTT client connections, and a single-server node supports millions of connections.
- Distributed cluster, fast and low-latency message routing, and single-cluster supports tens of thousands of routes.
- Extensible, support customized plugins, such as authentication and other functions.
- Comprehensive IoT protocol support, including MQTT, MQTT-SN, CoAP, LwM2M, and other TCP/UDP based proprietary protocol.