A peak fitting program for time-series signals, with sliders to adjust the parameters conveniently. Uses an non-linear optimization algorithm to decompose a complex, overlapping-peak signal into its component parts. The objective is to determine whether your signal can be represented as the sum of fundamental underlying peaks shapes. Accepts signals of any length, including those with non-integer and non-uniform x-values. Fits Gaussian, exponentially-broadened Gaussian, Lorentzian, Pearson, and Logistic shapes (expandable to other shapes). Can be operated either by mouse-controlled interactive sliders or by keyboard shortcuts. Includes a self-contained demo. See http://www.wam.umd.edu/~toh/spectrum/InteractivePeakFitter.htm for more information. Version 2.2, May, 2008, computes the area of each component peak using trapezoidal method.