ejabberd

ejabberd is an open-source, scalable real-time messaging platform built on Erlang/OTP. It provides an XMPP server for chat and presence, and can also act as an MQTT broker and SIP service for broader real-time and IoT workloads.

Key Features

• XMPP server with support for group chat, publish-subscribe, and many protocol extensions
• MQTT broker functionality for lightweight device and IoT messaging
• SIP service support and interoperability options for real-time communications
• Native clustering designed for high concurrency and large deployments
• Security-focused design with modern TLS support and configurable authentication options
• Multiple deployment options including packages and container images

Use Cases

• Team or consumer chat systems using XMPP (including multi-user chat)
• IoT telemetry and device messaging using MQTT
• Real-time communication backends that combine messaging and signaling needs

Limitations and Considerations

• Full capabilities often depend on correct selection and configuration of modules and protocol extensions
• Running large clusters typically requires operational expertise in tuning, monitoring, and database/storage choices

ejabberd is a mature, extensible platform suited to organizations needing a reliable messaging core at scale. Its multi-protocol approach makes it useful for both classic chat deployments and modern IoT-oriented messaging architectures.