Everything about corpkit is free and open-source. If you can code, please do consider contributing to the GitHub, by way of issue, fork or pull request. Nothing stops you from forking the GitHub Pages branch and adding some extra documentation, either!
Most of the current bugs will be for the GUI, which whose code resides in corpkit/corpkit-GUI.py. New releases of the corpkit app automatically copy this version of the code to the corpkit-app submodule, so don’t bother editing any of the code found there.