Regex Tester
Test and debug regular expressions with real-time matching
About Regex Tester
Test regular expressions with real-time match highlighting, capture group details, and pattern explanations. Debug complex regex patterns instantly.
- Real-time match highlighting as you type
- Shows all capture groups with their values
- Supports all JavaScript regex flags (g, i, m, s)
- Displays match count and positions instantly
- Tests patterns against multi-line test strings
Everything runs in your browser — your data never leaves your device.
How to Use Regex Tester
- Enter your regular expression in the pattern field
- Add flags (g, i, m, s) as needed
- Type or paste test text to see matches highlighted
Frequently Asked Questions
Which regex flavor does this tool use?
JavaScript's built-in RegExp engine, which supports most common patterns including lookahead, lookbehind, named groups, and Unicode property escapes.
What do the regex flags (g, i, m, s) mean?
g = global (find all matches), i = case-insensitive, m = multiline (^ and $ match line boundaries), s = dotAll (dot matches newlines). Combine flags as needed.
Can I test regex for other languages like Python or PHP?
Most basic regex patterns are cross-language compatible. However, some advanced features differ between engines. This tool uses JavaScript's regex, which covers the vast majority of common patterns.
Does it explain what my regex does?
The tool highlights all matches in real time and shows capture groups, so you can visually verify your pattern is working correctly against your test string.
