FRESHS is the Flexible Rare Event Sampling Harness System and is suitable for simulating rare event problems with different sampling algorithms like FFS and SPRES. The maintainers of the code are Kai Kratzer and Josh Berryman.

The development of the rare event sampling framework started at the Institute for Computational Physics (ICP) of the University of Stuttgart, Germany, by Kai Kratzer and Axel Arnold with the aim of using the simulation tool ESPResSo together with FFS in a comfortable way (at this time, the acronym 'FRESHS' did not yet exist). The project has then become a collaboration project with Josh Berryman at the University of Luxembourg with the implementation of the sampling algorithm SPRES and with the idea to create a flexible framework with a modular structure for different sampling algorithms. Therefore, FRESHS is developed in a close collaboration of the two groups.