Detect postal code, prefecture, and city mismatches
Warn customers without replacing your checkout fields
Choose warning-only, blocking, or off mode
Use Japan Post postal code data without storing addresses
Japan Address Guard helps Japanese online stores reduce failed deliveries caused by address mistakes. It checks the shipping address during checkout and warns customers when the postal code format looks wrong, the postal code does not match the selected prefecture, the city appears inconsistent, or the street address may be missing a block number.
The app does not replace the address fields customers already fill in. It only adds validation messages at the right moment, so merchants can improve address quality without changing the checkout experience. You can keep warnings non-blocking, turn validation off, or use blocking mode for high-confidence issues on paid plans.
Address data is processed only during validation. The app does not store shipping addresses and does not send them to third-party address APIs. If phone number checking is enabled on a paid plan, the phone number is also checked for format only and discarded on the spot; it is never stored.