The API is the programming interface between hotel software and the connected hardware. It is crucial for which devices work together. Data exchange, especially between products from different manufacturers, is only possible if the interface has been programmed accordingly. Our open ibelsa API is available to developers free of charge and already offers support for numerous third-party systems. A seamless link makes the administration of typical areas such as the cash register system, occupancy plans, housekeeping and contacts easier and clearer than ever before.