ZONA Technology, Inc. (ZONA) proposes to develop an on-line flutter prediction tool using the parameter varying estimation (PVE) methodology, called the PVE Toolbox, to ensure the flight safety during the flight flutter test and to prevent the damage to the wind tunnel hardware from the structural failure of the flutter model during wind tunnel flutter test. This tool can be applied to rapidly identify parameters, such as modal damping and frequency from test data measured at pre-flutter flight/wind tunnel conditions, then subsequently to assess the flutter boundary of aircraft/wind tunnel model in real time. In this PVE Toolbox, several system identification techniques are employed to consistently estimate the damping/frequency of the physical modes, followed by the implementation of Zimmerman-Weissenburger flutter margin, damping trends extrapolation, linear parameter varying modeling combined with mu-analysis, and thin plate interpolation method for flutter boundary prediction. Seamlessly integration of the PVE Toolbox into IADS (a real-time flight test data acquisition software system) will significantly improve the on-line flutter prediction capability of the PVE Toolbox. This robust, production-ready, and flight test demonstrated PVE Toolbox will provide flight/wind tunnel test engineers an on-line flutter prediction capability in the control room for decision-making during flight/wind tunnel flutter tests.