ZIP code guide
US ZIP Code Format Guide
ZIP code validation is one of the easiest places for address forms to become too strict or too loose. QA needs examples that cover normal five-digit ZIP codes, optional ZIP+4 values, and city/state matching.
Use this page when you need US ZIP code test data for checkout forms, shipping calculators, CSV imports, CRM demos, and address parsers.
What this adds beyond a basic address generator
Common ZIP shapes
Most product forms support a five-digit ZIP code and may optionally accept ZIP+4.
- 92126
- 10001
- 33130
- 92126-1234
Validation cases to cover
Good QA should include common accepted and rejected values.
- Five digits accepted
- ZIP+4 accepted when supported
- Letters rejected
- City/state mismatch detected
Consistency checks competitors usually skip
GenAddr keeps the fields in the same generated record aligned instead of mixing unrelated values.
- City and state stay together.
- ZIP code belongs to the selected city.
- Phone number uses a region-appropriate US format.
- Generated values are clearly marked as synthetic test data.
Example fields
- Five-digit ZIP
- 92126
- ZIP+4 shape
- 92126-1234
- City
- San Diego
- State
- CA
Example validation fixture
[
{ "city": "San Diego", "state": "CA", "postalCode": "92126", "expected": "valid" },
{ "city": "Miami", "state": "FL", "postalCode": "33130", "expected": "valid" },
{ "city": "San Diego", "state": "NY", "postalCode": "92126", "expected": "mismatch" }
]Responsible use
- All generated data is synthetic and does not describe a real person, household, or account.
- Do not use it for fraud.
- Do not use it for identity verification.
- Do not use it for payment verification.
- Do not use it to impersonate real people.
- Use it only for testing, QA, demos, development, and education.
Frequently asked questions
How many digits are in a US ZIP code?
The standard ZIP code is five digits. Some systems also accept ZIP+4, which adds a hyphen and four extra digits.
Is ZIP code enough to validate a US address?
No. ZIP code checks are useful, but production forms often also need city, state, street, and phone-format validation.
Does GenAddr generate city-matched ZIP codes?
Yes. US generated records use ZIP codes drawn from the selected city data so QA records stay internally consistent.