graphviz is a set of graph drawing tools and libraries. It supports hierarchical and mass-spring drawings; although the tools are scalable, their emphasis is on making very good drawings of reasonably-sized graphs. Package components include batch layout filters and interactive editors for X11, Java, and a TCL/tk extension.

Graphviz (short for Graph Visualization Software) is a package of open source tools initiated by AT&T Research Labs for drawing graphs specified in DOT Language scripts. It also provides libraries for software applications to use the tools. Graphviz is free software licensed under the Common Public License.