Regex Tester
Test regular expressions live with matches and replace preview.
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Matches
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Capture groups
Without the g flag only the first match is tested. Empty patterns match at every position, which is normal regex behavior.
How to use the Regex Tester tool
- Enter your regex tester in the fields above.
- Adjust any slider or type an exact number — the answer updates as you go.
- Copy the result and close the tab. Nothing you entered was sent anywhere.
About the Regex Tester tool
Enter a pattern (with optional g, i, m, u flags) and test text to see every match with its position and captured groups, plus a live preview of string.replace().
A reminder for daily use: regex cannot fully parse nested structures like HTML — use a parser for those, regex for the matches it was designed for.
Everything runs locally in your browser: no data is uploaded, no account is needed, and it works offline once the page has loaded.
Embed this tool
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