A port simulation methodology to predict port performance, based on probabilistic techniques, has been implemented in the software OptiPort. OptiPort is a robust, reliable, agile and user friendly tool to be used as a decision support tool in port management and planning. For a given case, OptiPort reproduces port operations from a holistic point of view and provides a set of indicators that measure the port performance, like waiting times or occupancy of berths and harbor services. The harbor performance is characterized from a statistical point of view. The software tool has been satisfactorily validated in Algeciras Port (Spain).