Kepler is described as 'Free open-source software system for designing, executing, reusing, evolving, archiving, and sharing scientific workflows.
Kepler's facilities provide process and data monitoring, provenance information, and high-speed data movement' and is an app in the education & reference category. There are five alternatives to Kepler for Mac, Windows, Linux, Web-based and Chrome OS. The best Kepler alternative is Simulink. It's not free, so if you're looking for a free alternative, you could try Xcos or OpenModelica. Other great apps like Kepler are Scicos and StochSD.