INFOS provides additional fitting programs that setup and use the FitSpec function for particular applications. The first of these is the FitTrace function, which simultaneously fits a series of spectra for which the amplitudes in those spectra are described by some user defined function, for example for fitting exponential decay in a time series of spectra. The second program is FitError, which analyzes a fit calculated with the FitSpec function to determine the approximate error on the various fitting parameters. Finally, FitEditor2D can be used to interactively edit a fit of a 2D spectrum.