UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.
Invision - Prototyping and collaboration for design teams
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
MockupCreator - MockupCreator is a tool to create mockups, prototypes and wireframes.
ARIS Express - ARIS Express is based on the proven ARIS methodology and industry standards.
Amplitude - Mobile analytics: come with questions, leave with answers