draw.io - Online diagramming application
Gephi - Gephi is an open-source software for visualizing and analyzing large networks graphs.
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Linkurious - Search and visualize your graph data through a simple web-based interface
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.
Visallo - Visallo helps intelligence analysts, law enforcement detectives, and fraud investigators produce...