XAID: a package for XAFS data analysis based on IDL. Manuel Sánchez del Río European Synchrotron Radiation Facility, BP 220, F - 38043 Grenoble Cedex 9, France Abstract. A set of IDL functions and procedures to perform basic XAFS data analysis has been developed. XAID provides the necessary tools to perform background substraction, Fourier transforms, Fourier filtering, etc. The library routines can be used as modules to be included in the users’s customized programs or for creating widget applications. Stand-alone main programs and Graphical User Interfaces to perform standard data analysis are also presented. XAID: a package for XAFS data analysis based on IDL.