Nyx is BSD-licensed and hosted on github. Contributions are welcomed.

Nyx is written in a mix of C++ and Fortran. The main driver, memory management, and parallelization are implemented in C++ (using the AMReX framework) and the physics kernels are written in Fortran. New code features are done either on the "development" branch or in a separate feature branch and periodically merged into "master". If you want to contribute to Nyx, clone the Nyx git repo, make your changes on "development" and then issue a pull-request to the Nyx "development" branch.