About RegEx Tester & Debugger
Free online regular expression tester and debugger. Write and test regex patterns with real-time match highlighting, capture group extraction, and flag controls. Includes a comprehensive regex cheatsheet and common patterns library. Test against multiple strings simultaneously.
Frequently Asked Questions
How do I test a regular expression?
Enter your regex pattern in the pattern field, add your test string below, and see matches highlighted in real-time with capture group details.
What regex flags are supported?
All standard JavaScript regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky).
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Privacy: This tool runs entirely in your browser. No data is sent to any server. Your input is processed locally using JavaScript and is never stored, logged, or transmitted. Lintly.cloud does not use cookies for tracking and does not require an account.