RegExp Visualizer
About
Visualize common RegExp structures like sequences, alternations, groups, character classes and quantifiers. Test matches alongside using the <a href="/regex-tester">Regex Tester</a>.
Runs locally in your browser. Export to SVG or PNG for sharing. For payloads embedded as URL/Base64, decode first via the <a href="/url-encoder">URL Encoder/Decoder</a> or <a href="/base-64-encoder">Base64 Encoder/Decoder</a>.
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.