Regex Tester
Test regex patterns, flags, groups, and replacements directly in your browser.
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Test regex matches and replacements instantly
Regex Tester evaluates patterns, flags, test text, capture groups, named groups, and replacement output in the browser. Use it to validate repeated text rules for logs, emails, dates, phone numbers, hashtags, and developer workflows.
Useful For
- Extract ERROR, WARN, and INFO log lines
- Validate email, date, and phone patterns
- Preview replacement output with capture groups
Good To Know
Custom patterns and test text are not included in shared links. Example links store only the selected sample name.
Developer Check
Generated code, regexes, meta tags, and config snippets should be treated as drafts and tested again in your runtime, security policy, and deployment environment.
How It Works
Inputs are calculated or converted in the browser whenever possible. Compare important results with the original source before using them. Reviewed on Jun 26, 2026.
Regex testing checks
Prepare pattern
- Confirm syntax and flags for the target language
- Review escaping and newline behavior
Test cases
- Include examples that should match and examples that should fail
- Cover Unicode, spaces, special characters, and empty strings
Before use
- Watch for slow patterns caused by excessive backtracking
- Retest in the production runtime's regex engine
Yes. Toggle common flags such as global, ignore case, and multiline to inspect match behavior.
Match results and group information help you check whether the pattern captures what you intended.
Testing runs in the browser by default, and regex patterns or sample text are not stored on the server.