Design and implementation of a WEB-based non-Markovian stochastic Petri net tool. This paper describes a new modeling tool for the anaysis of non-Markovian Stochastic Petri Nets (SPN). This tool, called Web-SPN, provides a discrete time approximation of the stochastic behavior of the marking process which results in the possibility to analyze a wider class of PN models with prd, prs and pri concurrently enabled generally distributed transitions. An example is used to show the features implemented into the tool.