Butterpy simulates star spot emergence, evolution, decay, and stellar rotational light curves. It tests the recovery of stellar rotation periods using different frequency analysis techniques. Butterpy can simulate light curves of stars with variable activity level, rotation period, spot lifetime, magnetic cycle duration and overlap, spot emergence latitudes, and latitudinal differential rotation shear.

Kiauhoku interacts with, manipulates, and interpolates between stellar evolutionary tracks in a model grid. It was built for interacting with YREC models, but other stellar evolution model grids, including MIST, Dartmouth, and GARSTEC, are also available.