Gear Design is a free Android application developed by José Fernández that calculates the main dimensions of spur and helical gears. The app is designed for individual gears and allows for an unlimited number of teeth and modules. Input data includes the number of teeth, normal module, pressure angle, helix angle (for helical gears), and the number of teeth measured (limited to three in this version). The app provides results such as the module apparent or tangential (for helical gears), axial module, modulo base, step normal diametral, and more.

In addition, Gear Design offers features such as a notice when non-standard modules are being used or when scour will occur on the teeth. The app also allows for the export of results to a file and offers a graphical explanation of the most important parameters. The app is available in seven different languages including English, Spanish, Chinese, French, German, Japanese, and Russian. The interface is simple and user-friendly. For any questions or improvements, users can contact the developer through the email provided within the app.