GD&T is a free Android application developed by Carl Zeiss, designed to help engineers and employees understand and interpret geometric dimensioning and tolerancing according to ISOThe app features a large range of definitions, including straightness, roundness, flatness, cylindricity, profile of a line, parallelism, squareness, angularity, position, concentricity, symmetry, and circular runout.

The app serves as a multimedia reference book and provides 25 animations to make it easier to understand the right handling of form and position tolerances in practice. It is an excellent resource for anyone interested in learning more about GD&T and its interpretation by examples. The app also includes basic information, form tolerance, profile tolerance, position tolerance, orientation tolerance, and runout tolerance. Overall, GD&T is a comprehensive and informative app that engineers and employees can use to improve their knowledge of geometric dimensioning and tolerancing.