MFEM and VisIt are key design codes in LLNL’s Center for Design and Optimization, which is developing algorithms that can optimize immensely complex systems in HPC environments. The MFEM library enables application scientists to prototype parallel physics application codes quickly, based on partial differential equations discretized with high-order finite elements. VisIt—a visualization, animation, and analysis tool—helps scientists and engineers interactively visualize and analyze data, from small (&lt101 core) desktop-sized projects to large (&gt105 core) leadership-class computing facility simulation campaigns. Learn more about the Center in the Science & Technology Review article “Leading a Revolution in Design.”