.*Regex Tester
Test regular expressions with live matching
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Common Patterns:
Matches: 0
No matches found
Regex Tester Complete Guide
Regular expressions (regex) are powerful text pattern tools used everywhere in software: searching, replacing, validating, parsing. Supported by all major languages — JavaScript, Python, Go, Java. This tool uses the JavaScript regex engine with real-time matching and replacement.
Enhanced Features
- Live Matching: Results as you type
- Match Highlighting: Yellow highlights in source text
- Replace Mode: $1, $2 capture group substitution
- Common Patterns: Email, URL, phone, IP, date, color, Korean, number — one click
- Capture Groups: Named groups (?<name>...) auto-extracted
Metacharacter Reference
| Char | Meaning |
|---|---|
| . | Any single char (except newline; with s flag includes) |
| ^ $ | Start / end (per-line with m flag) |
| * + ? | 0+ / 1+ / 0-1 |
| {n} {n,m} | Exactly n / n to m |
| [abc] [^abc] | Character set / negated set |
| \d \w \s | Digit / word char / whitespace |
| \D \W \S | Negations |
| \b \B | Word boundary / non-boundary |
| a|b | a or b |
| () (?:) | Capture / non-capture group |
| (?=) (?!) | Positive/negative lookahead |