Environmental monitoring plays a very important role for the health of people and the quality of life in daily places such as home, schools, offices and industries. The temperature, humidity and carbon dioxide concentration levels have to be limited in these environments. In this work, a system web-based environmental monitoring based on WSN technology is presented. Sensors, repeaters and a gateway form the WSN IoT system, where user-friendly interfaces are used to decrease the complexity of the set up. The control of the WSN and the gateway, and the data monitoring can be done through the web server running over the gateway along the software that provides user-friendly interfaces. The data visualization is displayed on a live data dashboard. The system is tested in a university and two industry environments.