Regex Tester – Test Regular Expressions Online | MZ Smart Tools House
Test regular expressions against sample text in your browser, review live matches and iterate on patterns without sending the test text to a remote service.
Check how a regular expression behaves against your own sample text and inspect the matches before using the pattern in code or data cleanup.
How it works
The worker compiles a JavaScript RegExp, collects matches and capture groups, and is terminated after the safety timeout.
Example
\d+ against 'Order 123 and item 456' finds 123 and 456.
How to use
- Enter the regular expression pattern.
- Add the flags supported by the tester when needed.
- Paste sample text.
- Review the matches and adjust the expression until it behaves as intended.
Key features
- Live regular-expression testing
- Sample-text matching
- Local browser execution
- Fast pattern iteration
Common uses
- Form-validation patterns
- Log parsing
- Text extraction
- Developer debugging
Frequently asked questions
Can regex still be expensive?
Yes. The worker timeout and input limits reduce UI-freeze risk but do not make every pattern intrinsically safe.
Are capture groups shown?
Yes. Numbered groups are included for each match.
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