Regex Tester & Validator

This case-insensitive regex matches postal box notations in various formats such as 'PO Box', 'P.O. BOX', 'POSTAL BOX', or a standalone 'BOX', optionally followed by whitespace, a '#' symbol, and a box number. It's commonly used for parsing and validating mailing addresses, detecting PO Box entries in checkout forms (e.g., to block them for physical shipping), and extracting box numbers from free-form address strings.