Abstract: The present invention relates to programming of electronic data carrier applications. In particular, it relates to an improved debugging method and system for chipcard applications. It is based on the principle to use a conventional standard communication protocol between chipcard and terminal application for debugging purposes as well. Primarily, protocol extensions are implemented by special commands according to said protocol, but carrying debug instructions instead of the usual business commands. A wrapper logic wrapping the card driver recognizes due to a control information given in the previous command that the response comprises debug information and sends it to the debug software.