Synergo 4.0 can be downloaded from our website for free. The program relates to Photo & Graphics Tools. The actual developer of the free program is HCI Group, ECE Department, University of Patras, Greece. The most popular version of the tool is 5.0.
From the developer:
The main use of SYNERGO is in developing diagrammatic representations like Concept Maps, Entity-Relationship diagrams and Flow Charts. SYNERGO puts emphasis on synchronous drawing activities of partners working at a distance. The target user of SYNERGO is higher education students and knowledge workers who use such representations in design and engineering courses.
You may want to check out more software, such as Iseult, GeoIPTC or Repeating Shapes, which might be similar to Synergo.