The standard OpenFF-Evaluator framework can estimate several condensed-phase physical properties, including liquid densities, dielectric constants, enthalpies of mixing, and hydration free energies. Here, we extend the OpenFF-Evaluator framework to include a workflow that estimates host-guest absolute binding free energies using either explicit solvent or generalized Born surface area (GBSA) implicit solvent. We have also modified the hydration free energy workflow to work with implicit solvents. The extension to the framework is illustrated in Figure . Currently, the OpenFF-Toolkit can assign small molecule parameters for the HCT and the OBC 28 implicit solvent models. Here, we chose to focus on the OBC2 variant of the OBC model for the implicit solvent, but other models can be implemented using the OpenFF-SMIRNOFF plugin ().