Regex Tester
Free regex tester with live highlighting. Write JavaScript regex, see matches and capture groups update as you type. Same engine your browser uses.
Runs in your browserUpdated Apr 26, 2026
Pattern
//
Test String
2 matches
Highlighted
Email ada@example.com or grace@test.io for info.
Frequently asked questions
›Which regex flavor is used?
JavaScript regex (ECMAScript), evaluated by the same engine your browser uses. Matches PCRE for most common patterns but differs on lookbehinds and named groups.
›What flags can I use?
g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), y (sticky).
›Are matches highlighted live?
Yes — every keystroke re-runs the regex and updates highlights immediately.
›Are capture groups shown?
Yes. Numbered and named capture groups are listed for each match.
›Is my input sent anywhere?
No — everything runs in your browser. Useful when testing regex against sensitive text.
›Is the regex tester free?
Yes — fully free, no signup.