About the Regex Tester
Regular expressions are powerful but unforgiving — a misplaced quantifier or unescaped character silently changes what matches. A live tester closes the feedback loop: you see exactly what your pattern captures as you type, including all matches with the global flag and the contents of each capture group.
This tester uses the JavaScript regex engine, so the behavior matches what you will get in Node.js and the browser. Everything runs locally, so you can safely test patterns against private text. Supported flags include global, case-insensitive, multiline, dotAll, unicode and sticky.
How to use the Regex Tester
- 1Enter your regular expression pattern.
- 2Toggle the flags you need (g, i, m, s, u, y).
- 3Type or paste the text to test against.
- 4Review highlighted matches and the list of capture groups.
Key benefits
- Live match highlighting as you type.
- Shows capture groups and match indices.
- Uses the real JavaScript regex engine.
- Private and instant.
Real-world examples
Validate an email pattern
Test a pattern against sample addresses.
Extract data
Use capture groups to pull fields out of log lines.
Frequently asked questions
Which regex flavor is used?+
JavaScript (ECMAScript), matching Node.js and browser behavior.
Why isn't my pattern matching?+
Check for unescaped special characters, missing the global flag for multiple matches, or anchors that don't fit your text.