StarUML - StarUML
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
Visual Paradigm - Looking for an affordable software with Enterprise Architecture tool, PMBOK tool, UML tool, Agile tool, BPMN tool and UX tool? Read this page for details.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.