PZFlex is a commercial software package for finite element analysis and virtual prototyping, developed by Weidlinger Associates Inc, USA. It was an outgrowth of the Flex family of codes developed for structural engineering. The PZFlex code uses both Explicit and implicit methods. It is a time domain solver that specializes in large wave propagation problems, with emphasis on problems featuring electro-mechanical materials such as piezoelectric ceramics. PZFlex stands for PiezoElectric Fast, Large and EXplicit.