Powerful cross-platform MQTT 5.0 desktop, CLI, and WebSocket client
...It is a publish/subscribe, extremely simple and lightweight messaging protocol, designed for constrained devices and low-bandwidth, high-latency or unreliable networks. To run MQTT Broker locally, EMQX is recommended: An Open-Source, Cloud-Native, Distributed MQTT Broker for IoT. After the MQTT is connected successfully, you can perform MQTT publish and subscription tests.
Device management, data collection, processing and visualization
ThingsBoard is an open-source IoT platform for data collection, processing, visualization, and device management. It enables device connectivity via industry standard IoT protocols, MQTT, CoAP and HTTP and supports both cloud and on-premises deployments. ThingsBoard combines scalability, fault-tolerance and performance so you will never lose your data.