CurveExpert 1.3 is a comprehensive curve fitting system for Windows. XY data can be modelled using a toolbox of linear regression models, nonlinear regression models, interpolation, or splines. Over 30 models are built-in, but custom regression models may also be defined by the user. Full-featured graphing capability allows thorough examination of the curve fit. The process of finding the best fit can be automated by letting CurveExpert compare your data to each model to choose the best curve. This program was designed to be simple but powerful, so that all users can obtain a model for their data quickly and easily.