The browser manufacturers worldwide are cooperating in the development of HTML5. The most powerful feature is the ability of the WebSocket application programming interface (API) [5]. One of the early purposes of the Web was to link a document using hyperlinks and facilitate document transfer. The HTTP protocol for the network is a model that handles this purpose. However, with changing times and with developments in the environment, the purpose of the Web no longer focuses only on sharing longer documents. In the HTML5 initiative, many specifications have been developed under the banner of the Web application environment that are not standardized and are inconsistent with the available plug-ins, which was one of its main purposes [6]. Among them is the specification for real-time two-way communication in a pure Web environment. Updated HTML5 specifications for web sockets, web browsers, and web servers allow sending and receiving data in real time, via an alwayson TCP connection [7]. Thus, the utilization of WebSockets, enabling full-duplex
communication using TCP sockets, is now possible. Instead of evolving from HTTP communication, merely using an existing web socket shows significant improvements in properties [8]. In particular, in the event-based Web application, which is based on real-time communication, the effect is even greater. The HTML5 WebSocket technology may be able
to receive information quickly via the push real time, and it may reduce the wait time for unnecessary network traffic. Therefore, in this paper, we conducted research on the HTML 5 WebSocket performance analysis by comparing the overhead depending on the number of concurrent users and the speed of the real-time multimedia communication.