SimpLie: a simple program for Lie algebras. SimpLie is an easy-to-use program for Lie algebra. It has been specifically written for level decompositions of infinite-dimensional Lie algebras, but it is not limited to that task. Its current features are: Calculation of Lie algebra properties based on Dynkin diagrams; Calculation of highest weight representations; Level decompositions; Visualization of root systems by means of [Screenshots Coxeter projections and Hasse diagrams].