Equalizer is an open source programming interface and resource management system for scalable OpenGL applications. An Equalizer application can run unmodified on any visualization system, from a singlepipe workstation to large scale graphics clusters and multi-GPU workstations. Equalizer is built upon a parallel OpenGL-based programming interface solving problems that are common to any multipipe application. The API is minimally invasive, making application porting as easy as possible while delivering maximum performance.