Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
Code2Flow - An easy solution to create product flows.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
DIagrams Through Ascii Art - Java command-line tool to convert ASCII diagrams to bitmaps.
ARIS Express - ARIS Express is based on the proven ARIS methodology and industry standards.
Flowchart.js - Draw SVG flow charts from simple text representations of the diagrams.