I have been using PRODRG for small molecules topology for years, but now I can't access it, I have emailed its developers but couldn't get any response. I want to use Gromacs forcefield, so I have only 2 options, one is ATB which is not free for new molecules, and another one was PRODRG. Kindly give me suggestions if you know any other way. I have tried Swissparam and switched to Charmm ff but it also didn't work and gave me errors with LJ and at the energy minimization step.