Regex Tester & Validator

Matches a time zone UTC offset from an ISO 8601 / RFC 3339 date-time, restricted to offsets actually in use worldwide: 'Z', whole-hour offsets between -12:00 and +14:00, plus fractional-hour exceptions like +05:45 (Nepal), +08:45 (Eucla), -03:30 (Newfoundland), and +12:45 (Chatham Islands). It uses a negative lookahead to reject '-00:00' (RFC 3339's unknown local offset) and invalid offsets such as +02:37. Useful for strictly validating the timezone suffix of timestamps in logs, APIs, and data imports.