RegExp Visualizer
About
Visualize common RegExp structures like sequences, alternations, groups, character classes and quantifiers.
Runs locally in your browser. Export to SVG or PNG for sharing.
Based on Regulex. Follows JavaScript RegExp syntax; invalid backreferences and decimal escapes in character classes are reported.
FAQ
Parsing failed?
Make sure the pattern is valid JavaScript RegExp. Unmatched parentheses, malformed quantifiers, or ranges like [z-a] will fail.
Unsupported features?
Octal escapes are not supported. Decimal escapes inside character classes are treated as errors. Invalid backreferences (e.g. \2 without a second group) throw errors.
How do flags work?
Toggle i/m/g below the input, or type flags after the last slash. They affect parsing and rendering (e.g. multiline anchors).
Why is repeating lookahead warned?
Repeats after lookahead don’t change matches. /a(?=b)+/ is equivalent to /a(?=b)/.
Best export quality?
Use SVG for crisp diagrams. PNG uses current SVG size; if you need bigger PNG, visualize then zoom your page and export.
Works offline?
Yes. Everything runs in your browser; no data is uploaded.