OBO-Edit is an open source, platform-independent application for viewing and editing OBO ontologies.
OBO-Edit is a graph-based tool; its emphasis on the overall graph structure of an ontology provides a friendly interface for biologists, and makes OBO-Edit excellent for the rapid generation of large ontologies focusing on relationships between relatively simple classes.
OBO-Edit began life as GO-Edit, a tool designed exclusively for use in editing the Gene Ontology. As more and more projects began to adopt the Gene Ontology standards for ontologies, GO-Edit became more flexible to accommodate the needs of more diverse ontologies. Eventually, GO-Edit became so general that it was renamed DAG-Edit, because DAG-Edit "ontologies" were a special sort of Directed Acyclic Graph.
DAG-Edit was a useful, fairly configurable tool. However, the code carried a lot of baggage from its former life as GO-Edit. And at its heart, DAG-Edit was really a program for editing labeled, directed graphs, not an ontology editor. DAG-Edit users began to have more and more complex needs for their ontologies. The Open Biological Ontologies project developed a new, much more expressive file format for describing ontologies. It was time for DAG-Edit to undergo another transformation.
So DAG-Edit became OBO-Edit, hopefully to be renamed for the last time. OBO-Edit has been (almost) completely recoded from the ground up. OBO-Edit is faster, more memory efficient, and more fully featured than its ancestors. OBO-Edit is a complete (if simple) ontology editor, with full support for the OBO ontology format.
Neat, huh?