Regex Tester

About Regex Tester

Type a pattern and the string is re-scanned on every keystroke, with each match wrapped in a highlight and every capture group listed underneath, numbered from one in the order the parentheses appear. The flag buttons toggle the six modifiers JavaScript supports: g runs globally instead of stopping at the first hit, i ignores case, m lets ^ and $ match line boundaries, s lets the dot cross newlines, u enables unicode property handling, and y anchors the search to the exact position of the last match.

The presets load well-tested starting patterns for the six things people search for most: email addresses, URLs, phone numbers, dates, hex colours and IPv4 addresses. Treat them as a base rather than a guarantee — an email pattern that satisfies RFC 5322 in full is thousands of characters long and rejects nothing useful in practice, so most real validators use a shorter, deliberately permissive form like this one. Watch out for the sticky flag: it can appear to match nothing when the scan position is not where you expect it.

• 100% free, no signup required
• Works entirely in your browser
• Your data never leaves your device