This article proposes an approach for developing configurable Internet of Things (IoT) end devices based on the ESP8266 SoC system. The MQTT protocol was used to ensure efficient communication between the devices, the control server, and the data collection system. This protocol enables efficient use of network resources and allows logical and hierarchical management of IoT devices. The proposed architecture is based on open-source software, including the OpenHAB platform, the Eclipse Mosquitto MQTT broker, and the MQTT communication protocol. Using application templates, it is possible to create smart lamps, motorized curtains, illumination and gas composition sensors (CO₂, CH₄), as well as temperature, pressure, and humidity sensors. The message processing speed of the developed devices was measured, and a unified testing platform was designed. The results demonstrated that the proposed approach makes it possible to develop IoT devices within a short period of time, support a large number of external devices, and provide satisfactory operational performance.