MQTTnet

Benchmarks show it processes approximately 150,000 messages per second in optimized scenarios, as stated in the README, making it suitable for high-throughput IoT and messaging systems.

Implements MQTT up to version 5 with a uniform API across versions, ensuring compatibility with modern devices and future-proofing applications.

Supports TCP, TCP+TLS, WebSocket, and in-memory channels for both client and server, allowing deployment in diverse network environments from local to web-based.

The ManagedMqttClient automatically handles connections, subscriptions, and message queuing for higher QoS levels, reducing boilerplate code for reliable communication.