Regex Tester
Test JavaScript regular expressions with local match highlighting, flags and capture group output. Everything runs locally in your browser.
Highlighted matches
Capture groups
| Match | Index | Full match | Groups |
|---|---|---|---|
| Capture groups appear after you test a pattern. | |||
JavaScript RegExp behavior
The tester uses the same browser RegExp engine your frontend JavaScript uses, so flags and syntax match real client-side code.
Capture group inspection
Review numbered groups, named groups and match positions without stepping through code or opening a console.
Private browser utility
Everything runs locally in your browser. Sensitive logs, tokens and sample payloads are not uploaded.
Related developer tools
Frequently asked questions
Is my regex or test text uploaded?
No. Everything runs locally in your browser with the JavaScript RegExp engine. Your pattern and text are not sent to Convertr servers.
Which regex flavor does this tester use?
This page uses JavaScript regular expressions, the same RegExp behavior used by modern browsers and Node.js.
Can I inspect capture groups?
Yes. The results table lists each match, numbered capture groups and named capture groups when your browser provides them.
Which flags are supported?
The tester supports common JavaScript flags including g, i, m, s, u, y and d when available in your browser.