an Open Source BPMN 2.0 / DMN 1.1 Modeler
CAM XML Editor for XML+JSON+Hibernate+SQL Open-XDX sponsored by Oracle
A free cross-platform editor for the DRAKON visual language.
UML diagram editor
A PlantUML editor written in Qt4
A graphical editor for PlantUML diagrams.
Prototype editor for the SDEM Mapping Language
An Eclipse plug-in for the IBM FileNet P8 Content Engine and CMIS