yEd Graph Editor
Free
yEd is a free general-purpose diagramming program with a multi-document interface.
D3.js
Open Source
D3.js (D3 for Data-Driven Documents) is a JavaScript library for producing dynamic, interactive data visualizations in web browsers.
PlantUML
Open Source
PlantUML is an open-source tool allowing users to create UML diagrams from a plain text language.
Tom Sawyer Software
Commercial
Tom Sawyer Software is a data visualization and social network analysis application.
Compare Graphviz with alternatives
Compare yEd Graph Editor and Graphviz and decide which is most suitable for you.
Compare Tom Sawyer Software and Graphviz and decide which is most suitable for you.