geometric design and strength check of spur gear with straight, helical and curved toothing. application is developed in ms excel, is multi-language and supports imperial and metric units. is based on ansi/agma and iso/din standards and support many 2d and 3d cad systems (autocad, autocad lt, intellicad, ashlar graphite, turbocad, autodesk inventor, solidworks, solidedge, pro/e).