AppComplete is a modelling and prototyping tool from CapableObjects.com , contains a UML-class modeller, contains a UML-state machine modeller, lets you execute your model including the state machines, uses the standard OCL as constraint and query language, can reverse engineer existing databases, contains a prototyper so that you can verify your thoughts, brings you ModelDrivenArchitecture MDA, is designed for DomainDrivenDesign, contains a documentation tool, enables you to publish the documentation in a html format, has TagExtensions so you can catch additional information, is fully compatible with ECO6; use your results in Visual Studio, is free for students.

If you cannot model your spec with AppComplete you should not send it to production. If you can model your spec with AppComplete use ECO to produce.