O3D is an open-source JavaScript API created by Google for creating interactive 3D graphics applications that run in a web browser window or in a XUL desktop application. O3D may be crafted for use in any application area; however, it is geared towards games, advertisements, 3D model viewers, product demos, simulations, engineering applications, control and monitoring systems, and massive online virtual worlds. O3D is currently in Google's incubation lab, and was originally built as a web browser plugin. Since 2010, O3D is a JavaScript library implemented on top of WebGL.