Equalizer is the standard middleware to create and deploy parallel OpenGL-based applications. It enables applications to benefit from multiple graphics cards, processors and computers to scale the rendering performance, visual quality and display size. An Equalizer application runs unmodified on any visualization system, from a simple workstation to large scale graphics clusters, multi-GPU workstations and Virtual Reality installations. Equalizer 1.2 is a feature release extending the 1.0 API, distilling seven years of development and decades of experience into a feature-rich, high-performance and mature parallel rendering framework and an object-oriented high-level network library. It is intended for all application developers creating parallel, interactive OpenGL applications. Equalizer 1.2 can be retrieved by downloading the source code or one of the precompiled packages.