Toxic App is a toilet queue management app facilitating usage of restrooms in an office. Based on the Arduino equipped with photoresistor, the IoT app monitors if someone is in the restroom and provides data to the web interface indicating which toilet is available. The web part of the solution, which can be integrated with a web browser, provides convenient and distraction-free information. With this approach, users can see if there are free toilets before even leaving their seats.The Toxic app is based on Arduino with photoresistor as a sensor & WiFi module to update status. The front-end part uses Angular with EmberFire as a data source part (it uses WebSockets for instant status update).