Regex Tester & Validator

Validates dates in YYYY-MM-DD format for years 1900-2099, enforcing correct day ranges per month: up to 31 days for long months (Jan, Mar, May, Jul, Aug, Oct, Dec), up to 30 for short months (Apr, Jun, Sep, Nov), and up to 29 for February via a lookbehind. Anchored with ^ and $ (multiline flags) so it matches complete date strings. Note it permits Feb 29 in any year, so it does not strictly enforce leap year rules.