Apps similar to Astah SysML include Enterprise Architect. It's paid, but Modelio is free. Other options are MagicDraw. In total there are three UML Modeling Tools like Astah SysML for Windows, Linux and Mac.
High performance and scalable visual modeling tool for the planning, design and construction of business architectures, software and systems. With customers based in all industries, Sparx Systems is a leading vendor of innovative modeling solutions.
Australia
MagicDraw is an award-winning business process, architecture, software and system modeling tool with teamwork support. MagicDraw UML can do comprehensive UML diagramming, reverse and forward engineering for Java and C++.
Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI. It allows to draw all UML2 diagrams and specific diagrams for business process modeling. It is easy and powerful with the capacity to add new functionalities to the application.
France
EU
