Regular Expression Tester
Debug a JavaScript regular expression against real sample text. Change the pattern and flags to see every match, index, capture group and named group immediately; no text is uploaded.
🔒 100% private — files never leave your browser
How to use the Regex Tester
- 1 Enter a JavaScript regular expression and its flags.
- 2 Paste the sample text you want to test.
- 3 Review matches, indexes and capture groups, then refine the pattern.
Frequently asked questions
Which regex engine does it use?
It uses the JavaScript RegExp engine built into your browser. PCRE, Python and .NET syntax can differ, so test again in the target runtime before shipping.
Can it show capture groups?
Yes. Each match lists numbered capture groups and named groups when the JavaScript engine provides them.
Is my test text sent anywhere?
No. Matching happens locally in your browser and the text never leaves your device.
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