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County lookup by ZIP code

Enter a ZIP code, get its county and FIPS code. Parishes and boroughs included.

Free, no signup.

THE API UNDERNEATH

GET /postal/33139?country=US

The county rides every ZIP lookup as district and district_name, so this page is one /postal call from your browser. Same endpoint on every plan, one pooled request per lookup.

ZIP code APIDistrict APITimezone by ZIP

QUESTIONS

What is a FIPS code?
The 5-digit federal code for a county. The first two digits are the state, the rest the county. Census data, health data, and most government files key on it.
Louisiana and Alaska?
Parishes and boroughs sit at the same grain and come back the same way.
Can a ZIP cross county lines?
Some do. The answer is the county at the ZIP's center point, which covers the large majority of its addresses.
Can I do this from code?
Yes. The county rides every GET /postal lookup as district and district_name. One pooled request.