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 and versatile local regressions. Interpolations include linear, cubic spline, bessel and monotonic splines, and a 'flexible' spline. Data smoothing functions include moving average, median filter, and Gaussian smoothing.