Regex Tester
Test regular expressions with live matching and highlighting.
Quick Reference
. Any character except newline\d Digit [0-9]\w Word char [a-zA-Z0-9_]\s Whitespace^ Start of string/line$ End of string/line* Zero or more+ One or more? Zero or one{n,m} Between n and m times(abc) Capture group(?:abc) Non-capture group[abc] Character class[^abc] Negated classa|b Alternation (or)\b Word boundaryFrequently Asked Questions
What regex flavors does this tool support?
The tool uses JavaScript's RegExp engine, which supports most common regex features: character classes, quantifiers (greedy and lazy), alternation, capturing and non-capturing groups, lookahead and lookbehind assertions, named groups, and Unicode property escapes. It covers virtually all common regex use cases.
What do the different flags mean?
The main flags are: g (global — find all matches, not just the first), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — dot matches newline), u (unicode mode), and y (sticky — match from lastIndex). You can toggle each flag independently.
How do I view capture groups?
The tool displays all capture groups for each match in a structured table. Named groups (using ?<name> syntax) show the group name alongside the captured value. This makes it easy to verify that your groups are capturing exactly the text you intend.
Can I test regex replacements?
Yes — enter a replacement pattern to see the substitution result in real time. The replacement supports $1-$9 for numbered groups, $<name> for named groups, $& for the full match, and $` and $' for text before and after the match.
Is there a quick reference for regex syntax?
Yes — the tool includes a built-in cheat sheet covering character classes (\d, \w, \s), quantifiers (*, +, ?, {n,m}), anchors (^, $, \b), groups and assertions, and common patterns. This reference stays visible alongside your testing area for quick lookup.