Xj3D is an open source X3D browser, developer library and test environment for real time 3D, virtual reality and augmented reality on the web, desktop or mobile device. It has been used to prototype many extensions to the X3D spec - physics, fog, 3D textures, CAD, device abstraction, binary formats and more all began life as Xj3D extensions. A primary focus of Xj3D is conformance to the X3D spec while still maintaining high performance. The milestone 1.0 release is available for Windows, Linux, Mac OS X, and Solaris. It implements CADGeometry, DIS, GeoSpatial, H-Anim, as well as extensions for Rigid Body Physics, Particle Systems, Clipping planes, Picking Utilities, Abstract Device IO.