SpinHarmony Suite (download link)
This suite includes the following three programs: Spinteract for refinement of magnetic interaction parameters to powder and single-crystal magnetic diffuse scattering data; Spinvert for refinement of atomistic models to powder magnetic diffuse scattering data; and Scatty for rapid calculation of diffuse-scattering patterns from atomistic models. It also includes a tutorial with worked examples using experimental data. Separate downloads of each program are available below.
Spinteract

Spinteract is a program for refinement of magnetic interaction parameters to magnetic diffuse scattering data collected on powder and single-crystal samples. The program was published in this paper. You can download it from this link.
Scatty

Spinvert

Spinvert is a program for refinement of atomistic models to powder magnetic diffuse scattering data for frustrated magnets, spin glasses, and other magnetically disordered materials. The program was published in this paper. You can download it from this link.