Here are the source code for the Generalized Parton Distributions through Universal Moment Parameterization (GUMP) program for global analysis of GPDs.

For GPDs calculations:

The Predictions.py file contains examples of generating PDFs and GPDs with GUMP parameters, which are obtained with the fitting program.

Caveat: the GPD evaluation can be slow since it involves QCD evolution in moment space and numerical contour integral to get back to x space.

Find more details at https://yuxunguo.github.io/GUMP-Global-GPDs/