This paper present under a general manner, a software elaborated by the authors and their research teams, during a research project. So, we have worked out a toolbox (SIMMECH) of an ample program, done by dr. Rusu a few years ago, entitled Pythagoras. Both Pythagoras and Simmech packages was performed using the Java platform. In this stage of research, Simmech toolbox is able to simulate planar linkages and robots only. The simulation of a mechanism or robot of the specified category begins with its building, using specialized buttons on the graphic interface of the program, then we may visualize the movement of the mechanism for a imposed segment of time and we can also visualize the kinematical diagrams of the elements or joints. We hope in future to extend our research to the spatial mechanisms and robots.