PoPS is open-source and freely available for anyone to use. There are two ways you can run PoPS:
PoPS 1.0 is currently available for download in R and GRASS GIS. Both versions of PoPS are wrappers around the PoPS Core C++ library for the Pest or Pathogen Spread Model.
All versions of PoPS provides the same functionality. The version you choose depends on your personal coding language preference. A Python version is under development and will be released soon.