Camunda - The Universal Process Orchestrator
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
jBPM - jBPM is a flexible Business Process Management (BPM) Suite.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
ProcessMaker - ProcessMaker is an easy to use BPM and workflow software solution. It is used to design, automate, and deploy business processes of any kind.
ARIS Express - ARIS Express is based on the proven ARIS methodology and industry standards.