Regex Tester β Test regular expressions live
Build and debug JavaScript regular expressions with live highlighting, capture groups, and replace preview.
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Presets:
How to Use
- Type a regex pattern in the top field.
- Toggle flags or pick a preset.
- Paste your test text β matches are highlighted live.
- Use the replace field to preview substitutions.
All processing is done in your browser, and files are never sent to a server.
Frequently Asked Questions
JavaScript's native RegExp (ECMAScript). Differences from PCRE: no recursion, slightly different lookbehind support.
Yes, syntax like (?<name>...) works.
No. Everything runs in your browser.