Free Online ZIP Code Validator

1. Type a 5-digit or 9-digit ZIP code (digits, optionally with a dash before the last four).
2. Read the validity check and the broad region the leading digit maps to.
3. Look up the city in an official USPS tool if you need street-level data.

US ZIP codes are 5 digits — or 9 with the optional ZIP+4 extension that identifies a smaller delivery segment. The first digit groups the country into 10 broad regions, from the Northeast (0, 1) to the Pacific (9). This is enough information to know whether 99501 is a real-looking code (Alaska, in the 9 region) without contacting a USPS database.

Form-validation builders plug the regex into client-side checks before submission. Mail-room staff cross-check ZIPs typed into shipping software. Data analysts cleaning address fields spot impossible codes quickly. This tool is a format checker — it does not look up the city or street, which would require a licensed copy of the USPS National ZIP+4 file (not freely redistributable).

Use it for client-side input validation, sanity-checking a number, or quickly identifying the region a code belongs to. Look up the city in an official USPS tool if you need street-level data.