Abstract: Web based operating system (WebOS) that provides user interface which is applicable to any types of platform is provided. According to the invention, user interface which is generated by WebOS, Web Desktop, Device, System, and Program are provided. The device followed by this invention ‘providing web based user interface’ includes: fixed size of body folder; menu bar which located at a specific location on the body folder for locating links in order to execute programs; sub-objects formed on the body folder; icon which is formed on the body folder for locating links for executing programs and connecting to URLs; and body frame which communicates with the body folder, menu bar, sub-object, and icon.