ZIP Code Checker
Enter a US ZIP code to see its city, state and county. Enter a city and state to list its ZIP codes. The data loads into your browser, so nothing you type is sent anywhere.
A match in this dataset is not a USPS delivery check. Street addresses and ZIP+4 need the USPS tool. Nothing you type leaves your browser.
How to use it
1. Type a ZIP code or a place
Enter a 5-digit ZIP code such as 10001, or a city and state such as Austin, TX.
2. Press Look up
The tool loads the data for the right state and finds the match.
3. Read the result
A ZIP code shows its place, state, county and map coordinates. A city shows every ZIP code listed for it.
Common questions
Where does the ZIP code data come from?
The data is the GeoNames US postal code file, licensed CC BY 4.0, retrieved on 2026-10-20. It holds 41,490 rows. GeoNames provides it as is and makes no promise of accuracy or timeliness.
Does this tool check that a ZIP code is valid for delivery?
No. It checks whether the code appears in the GeoNames file. USPS creates, changes and retires ZIP codes, and this file can lag behind. For mail, confirm the full address with the USPS ZIP Code Lookup tool.
Can I look up a street address or a ZIP+4?
Not here. A street address needs USPS address data, which this static page does not hold. If you type a ZIP+4 such as 12345-6789, the tool uses the first five digits.
Why does a city show more than one ZIP code?
A city can span several ZIP codes. Each ZIP code in the file has one listed place name, so the list for a city is every ZIP code that carries that name.
Does my input leave my browser?
No. The page downloads the data file for one state, then looks up your input on your own device. The tool sends what you type to no server.