For managing application data of different contactless card applications for a plurality of mobile communication devices (2), a card emulation module and application data for contactless card applications are transferred (S2, S3) by a computer system (1) to one of the mobile communication devices (2). The card emulation module is configured to control the mobile communication device (2) to emulate a contactless card module and to execute data transactions (S6, S7) via a close range wireless communication interface of the mobile communication device (2) using the application data. The computer system (1) maintains (S20, S30, S40, S50, S60) for the mobile communication devices (2) a card database with representations of the card emulation modules and their application data. The computer system (1) makes it possible to manage centrally and flexibly the application data of different contactless card applications and different application providers for a plurality of mobile communication devices (2).