From CyberBio Renovations:
This Excel Addin incorporates curve fitting functionality using non-linear least square regression analysis. This is equipped with intuitive tutorials for user to start using immediately. Using user's original Excel sheet filled with data and assigned equation, the "CurveFitter ExcelAddIn" calculates best fit parameter values with standard deviation. The result will be written in a new Excel Sheet with a chart in the same Excel Workbook. Numerical method (Newton-Raphson and integration) is enabled with flexible custom equation. This is also capable of Global fit with multiple data sets.