SuperSocket
Extensible socket server application framework for .NET
...The framework supports multiple protocols, including TCP, UDP, and WebSocket, and gives developers a modular architecture for protocol parsing, session handling, command processing, and server hosting. It is suitable for chat servers, game servers, IoT gateways, telemetry services, industrial systems, and other real-time network applications. SuperSocket is designed to be flexible enough for custom binary or text protocols while still offering reusable abstractions for common server patterns. It is most useful for .NET teams that need robust networking infrastructure with room for domain-specific protocol logic.