Regex Tester
Test regular expressions against any text with live match highlights.
hello@example.comat 14sales@example.orgat 35What this tool does
Regular expressions are powerful but unforgiving — one wrong character and your pattern matches nothing (or everything). This tester runs your regex live against test input, shows every match with its position, and surfaces syntax errors clearly.
Why it matters
Regex Tester saves you time and removes guesswork from everyday developer tools work. Live updates as you type — and because everything runs in your browser, your data stays private and results are instant.
- Live updates as you type
- Error messages for bad patterns
- Shows position of every match
How to use
- Enter your pattern (without the slashes).
- Add flags (g, i, m, s).
- Paste your test string and watch matches update live.
Example output
// Formatted, validated output
{
"status": "ok",
"result": "..."
}Real-world use cases
- • Building validation rules
- • Extracting data from logs
- • Cleaning text with substitutions
Tips & best practices
- • Escape special chars: . * + ? ( ) [ ] { } | \ ^ $
- • Use the 'g' flag for all matches, not just the first
- • Test edge cases — empty string, very long input, special chars
Frequently asked questions
Which regex flavor is this?
JavaScript's RegExp — close to PCRE but not identical.
What do the flags mean?
g = global, i = case-insensitive, m = multiline, s = dotall, u = unicode.
Is there a length limit?
Pattern and text can each be tens of thousands of characters.
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