Internet of Things system is developing for many years. The system includes technologies and assemblies which are connected to the Internet. Primarily, it consists of four connected components which include devices, communication, data processing and user interface. By combining different connected devices it is possible to connect and analyse dana. Whole system can function without any human intervention. The topic of this final theisis is network communication within the Internet of Things. Developed applications are programmed in Java environment. It is describing development and most common technologies that are used in Internet of Things, which can be implemented with minimal investment using free tools and software environments. Within the practical part of the work, Spring Boot application was developed, which enables the display of collected data from Raspberry Pi device to which a DHT11 sensor is connected. There is program implemented in the device, which enables sending data from sensor and communicates with database on application via a wireless network. The data is sent every five seconds and they are storing in PostgreSQL database. During the application developement, Postman tool was used to make tests. The entire system was developed using free open source tools and technologies so it can be possible to upgrade it. There are cheap and affordable components implemented. We can conclude that it is possible to develop whole Internet of Things system consisting of software and physical assembly with minimal investments. Testing of individual requirements gives visibility of funcionality of the entire system.