The present report reviews a set of probabilistic seismic hazard analysis (PSHA) computer programs (CRISIS, EQRM, NSHMP, OpenSHA, and SEISHAZ) proposed as possible platforms for the development of the GEM1’s hazard engine. The analysis is supplemented by including a number of additional software (FRISK88M, MoCaHAZ, MRS, OHAZ, and SEISRISK IIIM) considered important to obtain a more comprehensive understanding of the current state-of-the-art in PSHA. The report is organized into two sections. The first describes the main properties of each PSHA program on the technical (e.g. the programming language) and scientific level (e.g. the PSHA source typologies supported). The second illustrates, for a subset of the selected software, a simple benchmarking exercise aimed at understanding the behaviour of the programs, and to compare the results provided for very simple cases. The review of the selected PSHA software proved to be a very useful exercise to delineate the desirable properties for the GEM1 seismic hazard engine and shows that OpenSHA can accommodate the GEM1 IT and hazard specifications better than the other evaluated software.