COSMO is a free Android app developed by COSMO GmbH that provides a comprehensive range of professional tools for HVAC technicians. The app is designed to be used on-site, giving technicians access to data sheets, spare parts, and more. The app offers a well-designed calculator to help with planning, including a unit converter that can convert a variety of values quickly. The app also includes a heat/power calculator (Q = cm∆T), which can calculate the heating power required to heat a certain amount of water. The app also has a built-in scanner that can display installation instructions via QR codes or identify barcodes. COSMO® is a valuable tool for HVAC technicians, providing professional support for heating, radiators, air conditioning, and ventilation.