To predict reaction pathways in-silico, we developed the ReactionRank (RR) platform. RR is a High-Performance Computing solution for the efficient scanning of elementary reaction space, in a fully unattended and system-agnostic mode. It records energy vs. reaction coordinates and tabulates unimolecular and bimolecular elementary reactions, cataloguing a full list of reactant, transition state and product structures and activation energies. Reaction scans can be constrained based on molecular weight, max. activation energy and other parameters. The final catalogue yields prevailing pathways and may also be used as input to Kinetic Monte Carlo system propagation and generation of ReaxFF parameters.