It can read and write graphs in a varity of formats, as well as render them via its own grid-based layouter.

It has export filters for Graphviz, VCG (Visualizing Compiler Graphs), GDL (Graph Description Language) and GraphML. Import filters are for Graphviz, VCG and GDL.
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Since the layouter works on a grid (manhattan layout), the output is most useful for flow charts, network diagrams, or hierarchy trees.

Graph::Easy has an easy-to-understand, compact and human readable graph description language.