Regex → NFA / DFA Visualizer

Type a regular expression and watch it compile the way an engine does: first to a Thompson NFA (with ε-transitions), then via subset construction to a DFA. Both are drawn as state machines. Enter a test string and step through it to see the active states move. Sibling to the plain regex tester.

Regular expression

Test string

Supported syntax

abc — literal characters
. — any single character
a|b — alternation
a* — zero or more
a+ — one or more
a? — optional
(ab) — grouping
[a-z] — character class
[^0-9] — negated class
\d \w \s — digit / word / space
\. — escaped literal