Catoki present a new alternative to MATLAB IDENT GUI. This is friendly interface for system identification SISO. CaToKi is based in a regular course of Identification based in Ljun Book. You can obtain models of easy way: ARX, ARMAX, Outpur-Error and Box Jenkis. Plot your input-output dates. Compare plots, residuals plots, bode, step, impulse, frequencial uncertainty and poles and zeros. In Matlab Workspace you can see the model obtained. Is Easy to use and free.