There used to be a nice web interface here, enabling users to upload their molecular configuration files (xyz, pdb, you name it) and get back the UFF topology ready to be used with GROMACS.

Unfortunately, we cannot provide this service anymore.

However, OBGMX was built on top of free software so I made it available on GitHub, together with a pre-compiled binary named obgmx which works fine in a virtual machine running Ubuntu 16.04 LTS. Please refer to the README file in the distribution for installation instructions.

Please notice that I cannot support this software anymore, so if it does not work (or produces meaningless topologies) it is very unlikely that I will be able to help you.