Graphynx!

Graphviz is open source graph visualization software. It has several main graph layout programs. It also has web and interactive graphical interfaces, and auxiliary tools, libraries, and language bindings.

Gephi is an open-source software for visualizing and analyzing large networks graphs. Gephi uses a 3D render engine to display graphs in real-time and speed up the exploration. Use Gephi to explore, analyse, spatialise, filter, cluterize, manipulate and export all types of graphs.

Social Network Visualizer (SocNetV) is a cross-platform, user-friendly application for the analysis and visualization of Social Networks in the form of mathematical graphs, where vertices depict actors/agents and edges represent their relations.

A web-based NFA and DFA construction and testing tool.

JFLAP is software for experimenting with formal languages topics including nondeterministic finite automata, nondeterministic pushdown automata, multi-tape Turing machines, several types of grammars, parsing, and L-systems. In addition to constructing and testing examples for these, JFLAP allows one to experiment with construction proofs from one form to another, such as converting an NFA to a DFA to a minimal state DFA to a regular expression or regular grammar.

GraphShop is the Graph Theory Workshop, an interactive software environment for Graph Theory research and applications. It contains a visual "point and click" interface for graph creation and manipulations, as well as an integrated scripting environment (using ECMAScript) linked both ways with the GUI systems. This means that one can create a graph with scripting, examine and modify it with the visual interface, and then run a custom script algorithm on the result.

the free and opensource(GPL) software framework to work on graphs and social networks.

GraphThing is a tool that allows you to create, manipulate and study graphs. These "graphs" are mathematical objects that describe relationships between sets; they are not 2D plots, charts, or anything similar to that.

Rin'G is an environment for the study and implementation of Graph Theory algorithms that allows users to view interactive, step-by-step animations of their executions.

Rocs aims to be a Graph Theory IDE for helping professors to show the results of a graph algorithm and also helping students to do the algorithms.

Need to test a deterministic finite automaton for an upcoming course assignment, or just curious? Then you've come to the right place! DFA Tester is a simple and intuitive application to build and test deterministic finite automatons.

Polinode is a tool for collecting information on relationships between people. For example, who works with whom? Who do people go to for advice? And any other question you like. With a powerful survey tool to collect the data and integrated visualization and analysis functionality to explore the network data, Polinode aims to help organizations and non-profits cut through complexity.

blockdiag and its family generate diagram images from simply text file.