An image processing system which is capable of easily customizing a user interface to be displayed on a client computer, according to user's intended use, preference, and/or the like. An image processing apparatus 101 is operable when receiving an operating request from a web client 120, to perform processing corresponding to the received operating request, and transmits to the web client 120 a redirect instruction for commanding access to a display processing service web server 110 as a response to the operating request. The web client 120 is operable when receiving the redirect instruction from the image processing apparatus 101, to access the display processing service web server 110 according to the received redirect instruction. The display processing service web server 110 is operable when being accessed from the web client 120 according to the redirect instruction, to transmit information for display according to a request from the web client 120, to the web client 120.