Abstract: The present invention relates to an add-on architecture which can be applied to a network device. A network device for processing at least one or more applications, according to one embodiment of the present invention, comprises: a host S/W processing module which receives a key event for executing a specific command, and transmits the received key event to an add-on system manager, said add-on system manager which checks a focused specific application from among one or more applications currently being executed, and which transmits the received key event to the focused specific application; and an add-on application which processes the received key event.