Janus is a general-purpose WebRTC media server and gateway written in C. It provides a modular architecture with a core daemon that dynamically loads plugins for various use cases (video conferencing, audio bridging, streaming, SIP, etc.), transports (HTTP, WebSockets, MQTT, RabbitMQ, Unix sockets), and event handlers. The server handles ICE/DTLS/SRTP for WebRTC peer connections, relays RTP/RTCP media between participants, and supports advanced features like simulcast, SVC, recording, and post-processing. A JavaScript client library (janus.js) is provided for browser integration. The system is production-grade, actively maintained, and widely deployed.