Disclosed are various embodiment(s) for a digital device and a service processing method by the digital device. Here, a digital device according to an embodiment of the present invention comprises: a display processing unit for transmitting a first lifecycle message, a second lifecycle message, and coordinate information on the size and the position of the second application in a display, to Webkits of a first application and a second application, when a plurality of applications exist in the foreground; a display engine comprising a main sink for the first application and a sub sink for the second application; and a video processing unit for connecting the first application to the main sink of the display engine according to an identifier and a connection request received from a Webkit of the first application and connecting the second application to the sub sink of the display engine according to an identifier and a connection request received from a Webkit of the second application. Therefore, the digital device outputs a video source of the plurality of applications existing in the foreground.