WebSockets

• Socket.IO - Realtime application framework (Node.JS server).
• ws - The fastest cross platform WebSocket library for Node.js.
• µWS - Highly scalable WebSocket server & client library.
• ClusterWS - Lightweight, fast and powerful framework for building scalable WebSocket applications.
• uws - Ultra fast, simple, secure & standards compliant web I/O for the most demanding of applications.
• primus - An abstraction layer for real-time frameworks to prevent module lock-in.
• sockjs-node - WebSocket-like object. SockJS gives you a coherent, cross-browser, Javascript API which creates a low latency, full duplex, cross-domain communication channel between the browser and the web server.
• faye - A set of tools for simple publish-subscribe messaging between web clients.
• deepstream.io - Open source server for realtime record synchronization and messaging.