Regex Tester
Test a regular expression pattern against sample text. Review matches, captured groups, and pattern errors.
Regex Tester tool
JavaScript regular expression syntax is used. Duplicate flags or invalid patterns will show an error.
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Privacy: regex evaluation runs locally in your browser. No pattern or text is stored or transmitted.
Enter a JavaScript regex pattern and optional flags, then test it against input text. In replace mode, the tool also applies a replacement string.
Examples
- \b\w4\b with g finds 4-letter words
- \d+ with g finds all number sequences
- (cat|dog) with i matches either word case-insensitively
FAQ
- What does this regex tester do?
It tests a regular expression pattern against input text and shows matches, groups, flags, and errors.
- Which flags are supported?
Common JavaScript regex flags are supported, including g, i, m, s, u, and y.
- What happens if the pattern is invalid?
The tool shows a validation error and does not attempt matching until the pattern is corrected.
- Are my patterns or test strings stored?
No. Everything runs locally in your browser and is not stored or transmitted.