Résumé : This paper presents the development of an open-source object-oriented program, named OpenMOOR, for static and dynamic analyses of mooring systems in ocean renewable energy applications, including offshore wind turbines and wave energy devices. The program is developed for cross-platform applications. It can be used as a standalone software or a dynamic linking library for developing coupled models of the moored structures/devices. A finite difference model of mooring cables is adopted for solving the motion of a single cable which can deal with the hydrodynamic effect, cable bending/torsional stiffness and nonlinear strain-tension relationship. Parallel computing is implemented for efficient analysis of a mooring system consisting of multiple cables, as common in the practice. OpenMOOR has then applied to analyse a single mooring cable under forced harmonic motions at the top end. The cable responses are found to agree well with the experimental data in the literature, which validates OpenMOOR.