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Regex Tester – Test Regular Expressions Online Free
TrendingTest and debug regular expressions with real-time match highlighting instantly. Supports capture groups, replace preview, and all JavaScript regex flags.
Regex Tester
Test, debug and explore regular expressions in real time
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Quick reference
.Any character (except newline)\dDigit [0–9]\DNon-digit\wWord char [a-zA-Z0-9_]\sWhitespace^Start of string / line$End of string / line*0 or more (greedy)+1 or more (greedy)?0 or 1 — or lazy quantifier{n,m}Between n and m times(…)Capture group(?:…)Non-capturing group(?=…)Positive lookahead[abc]Character classa|bAlternation (a or b)What is Regex Tester?
Interactive regex tester with real-time match highlighting, capture groups, and replace preview. Test patterns against sample text, debug issues, and learn syntax with visual feedback. Supports all JavaScript flags (g, i, m, s, u, y). Includes common regex library and cheat sheet.
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Regex Tester Features
Real-Time Testing
See matches instantly as you type
Visual Highlighting
Color-coded match highlighting
Capture Groups
Display groups with values and indexes
Replace Preview
Test replacements before applying
Regex Tester FAQ
All JavaScript flags: g (global), i (case-insensitive), m (multiline), s (dotall), u (unicode), y (sticky).
Yes. Tool includes replace preview with backreferences ($1, $2) and named captures ($<name>) support.
Common issues: unescaped special characters (. * + ?), missing 'g' flag for multiple matches, case sensitivity (use 'i'), or multiline mode (use 'm').