A new Test Driver for computing the Gibbs free energy of an arbitrary crystal at a specified temperature and pressure is now available in OpenKIM (DOI: 10.25950/bb22c884). By comparing the results for different phases of the same chemical system (i.e. different Tests associated with this Test Driver), finite temperature and pressure phase stability can be determined. As part of the Crystal Genome (XtalG) framework, results will become available on the material pages accessible through the "Search for Material" interface on openkim.org as they are computed. However, because of the computational cost of each calculation, we expect a large backlog. To address this, we have developed a "Run Request" system that allows users to prioritize specific calculations that are of intetest to them. See the announcement here. As with all XtalG Test Drivers, it is also available as a standalone Python class, in this case GibbsFreeEnergyCrystal, as part of the kimvv Python package.