Graphviz.
Non-trivial graphs will make it produce hard-to-read output, and you can try fiddling with it forever to get better output. But it's still the first thing I reach for when I have to make a graph.
Non-trivial graphs will make it produce hard-to-read output, and you can try fiddling with it forever to get better output. But it's still the first thing I reach for when I have to make a graph.