Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
ReqView - Simple and powerful requirements management tool enabling easy requirements gathering, traceability tracking and offline collaboration.
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
Reqtify - Reqtify is an easy to use, interactive application for managing requirements.
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.
Jama Connect - The Leader in Requirements Management Solutions