Web-based simulation (WBS) systems offer tradeoffs between user interactivity and hardware requirements striking to seek a balance between the differing concerns. Server-based systems offer little interactivity or concurrent visualization capabilities, while client-based systems have increased hardware requirements asking the user to provide high-end workstations. Concurrent visualization of simulation output proves execution intensive, or unusable in some situations. Creating an execution efficient and user friendly WBS system greatly improves user experience while gaining all of the benefits inherent in a web-based system such as high accessibility and ease of maintenance. In order to provide a usable concurrent visualization WBS this thesis developed the Web-Based Queuing System Simulation System (WebQS3). WebQS3 splits the responsibilities of simulation execution and simulation visualization into a client-server environment; the client is responsible for the visualization display and server is responsible for simulation execution. The system differs from many previous WBS systems in that the client-side application is developed using web-standard technologies such as HTTP, XML, SVG, and ECMAScript instead relying on Java Applets and associated technologies. Using web-standards as the foundation of the client agent opens the visualization and model construction functionality to any user that accesses the application using a web browser while also making the application more scalable in terms of user load. Implementing the client with web-standards also included the development of an asynchronous client-server communication protocol as opposed to traditional synchronous communication protocols used by Java WBS systems. The asynchronous protocol demonstrates similar or better execution performance than similar synchronous communication protocols in most quality characteristics. By creating a WBS system using web-standards implemented in most modern web browsers any user may visit the WebQS3 site and have simulation tools available for use. Providing simulation services on the web makes eases the creation of simulation models my making the tools to readily available while facilitating information sharing and collaboration over the web. The WebQS3 system serves as a model to drive research in WBS systems away from proprietary Java technologies to web standards for front-end visualization technologies. / Master of Science