AbstractMotivationThe generation of parameter files for molecular dynamics (MD) simulations of small molecules that are suitable for force fields commonly applied to proteins and nucleic acids is often challenging. The ACPYPE software and website aid the generation of such parameter files.ResultsACPYPE uses OpenBabel and ANTECHAMBER to generate MD input files in Gromacs, AMBER, CHARMM, and CNS formats. It can now take a SMILES string as input, in addition to the original PDB or mol2 coordinate files, with GAFF2 support and GLYCAM force field conversion added. It can be installed locally via Anaconda, PyPI, and Docker distributions, while the web server athttps://bio2byte.be/acpype/was updated with an API, and provides visualization of results for uploaded molecules as well as a pre-generated set of 3738 drug molecules.Availability and implementationThe web application is freely available athttps://www.bio2byte.be/acpype/and the open-source code can be found athttps://github.com/alanwilter/acpype.