What's this?
This tool shows you the deterministic and nondeterministic automata that some regular expression engines would use to parse your expression. Besides the educational use, it's nifty for debugging your expressions - just follow the little arrows and see where they go wrong.


  • Single circles are normal states.
  • Double circles are accepting states.
  • Arrows are transitions between states, labels represent the legal input.

Learn more
Read more about how this works at my blog binarysculpting.com. The graph generation is powered by Piglet, the fluent parser generator. Follow me on twitter @Perdervall.

Want to share your graphs? Press enter in the regular expression box and copy the URL of the page to get a direct link to your graph.

Nondeterministic automata

Deterministic automata