ParFlow-CLM is an advanced, massively parallel hydrologic model specifically tailored for supercomputing environments, serving as a benchmark for supercomputing centers. It simulates variably saturated groundwater flow and overland flow while integrating land-surface processes such as evaporation and transpiration through the Common Land Model (CLM). The model’s application spans from test sites to continental scales, operating on sub-daily to climate time scales, and is utilized for scientific research as well as quasi-operational purposes globally. Moreover, ParFlow is a vital component of the Terrestrial Systems Modeling Platform (TSMP), which comprehensively addresses the terrestrial water and energy cycle from bedrock to the atmosphere.