jSpin is a graphical user interface for the Spin model checker that is used for verifying concurrent and distributed programs. The user interface of jSpin is simple and consists of a single window with menus, a toolbar and three adjustable text areas. Spin option strings are automatically supplied and the Spin output is filtered and presented in a tabular form. All aspects of jSpin are configurable: some at compile time, some at initialization through a configuration file and some at runtime.