Data Curve Fit Creator Add-in is an easy-to-use data analysis add-in for Microsoft Excel. It adds curve fitting, interpolation, and data smoothing functions to Excel. Curve fitting functions include polynomial fits and a versatile local regression (loess) function. Interpolations include linear, cubic spline, bessel and monotonic 'constrained' splines, as well as a 'flexible spline' that allows you to specify the slope at each data point. Cubic spline function coefficients and slope can also be returned. Data smoothing functions include moving average, median filter, and a Gaussian smoothing filter. Data Curve Fit Creator Add-in also includes automatic sorting and data repair functions.