Abstract: This paper presents the implementation of a design tool, written in Pascal language, of a classic design method of wind turbines based on Blade Element Momentum Theory. The open source integrated development environment Lazarus was used. The software allows the user to visualize the changes in turbine geometry caused by the change in design parameters and the two design methodologies that are possible. Results that validate the algorithm according to the literature are shown. Characteristics of a wind turbine designed with a proper airfoil are also presented. The tool familiarizes the user with the open source philosophy and gives data to the construction of wind turbine models to experiments.