The Virtual World Framework (VWF) is a browser-based collaborative simulation system designed with the goal of creating content in a shared immersive space. For the Modeling & Simulation community, the VWF represents an evolution of the traditional online learning model by allowing the integration of three dimensional environments with other, more typical, content. Traditionally, offering learners an experience in such an environment required the instructional designer to craft content in some external system, often requiring specialty plug-ins and equipment. Many of these systems (i.e. Second Life, or OpenSim) require authors to learn new programming languages and methods that are not typically taught to instructional designers. By leveraging the web as a platform, the VWF makes it possible for a much wider range of authors to create immersive environments. Additionally, the VWF makes deploying this content to the end user much simpler than traditional immersive training packages. While other simulation environments require desktop software installation or browser plugins, the VWF uses cutting edge HTML5 capabilities to deliver its content to a variety of devices like desktops, tablets, and even phones, without any effort by the end user. Users simply type in a URL as they would for any website, and they can access the environment seamlessly. This has powerful benefits; including allowing immersive experiences on computers with strict security that prohibits many traditional solutions. Finally, the VWF architecture makes hosting a server simple. The VWF builds the simulated environment on each client, allowing the server to manage only synchronization. This allows a server to host many users while utilizing little bandwidth and computational power. This paper will describe the VWF architecture in detail and explain how the design decisions support the goal of wider access to immersive simulation.