Postal code guides
Guides on postal code validation, ZIP code distances in Excel, choosing a ZIP code API and when to use a database download instead.
Guide
ZIP code database vs API
Should you download a ZIP code database (CSV) or use a ZIP code API? Compare cost, freshness, coverage, maintenance and performance, with recommendations by use case.
Tutorial
How to validate postal codes
Postal code regex patterns for the US, UK, Canada, Germany and 16 more countries, code examples in JavaScript, Python and PHP, and when a regex is not enough.
Tutorial ยท Excel & Sheets
Distance between ZIP codes in Excel
Calculate miles or kilometres between ZIP codes in Excel and Google Sheets with the Haversine formula, or fetch distances directly with the WEBSERVICE function.
Comparison
Best ZIP code APIs in 2026
Comparison of ZIP and postal code APIs in 2026: zipcodestack, Zipcodebase, Smarty, the USPS API, GeoNames and more. Coverage, features, free tiers and pricing.
Postal code API
Get this data in your app
zipcodestack looks up, validates and searches postal codes in 149 countries: city, state, coordinates, distances and radius search, as JSON.
/v1/search documentation International postal code API All documentation
300 free requests every month. No credit card required.
GET https://api.zipcodestack.com/v1/search?codes=10001&country=us
{
"results": {
"10001": [{
"postal_code": "10001",
"country_code": "US",
"latitude": 40.7484,
"longitude": -73.9967,
"city": "New York",
"state": "New York",
"state_code": "NY",
"province": "New York"
}]
}
}