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PostalCodes vs US ZipCode

Same instrument, two spec sheets — measured, not claimed.

APIPostalCodesNEW—US ZipCodeNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthnoneapiKey
CORSnoyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

PostalCodes vs US ZipCode: common questions

Which is more reliable, PostalCodes or US ZipCode?

On our scheduled checks, US ZipCode leads on measured uptime — PostalCodes at —% versus US ZipCode at —% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.

Do PostalCodes and US ZipCode need an API key?

PostalCodes needs no key, while US ZipCode requires a free API key. If you want to start calling without signup, reach for PostalCodes first.

Can I call PostalCodes and US ZipCode from the browser?

Only US ZipCode is browser-friendly — it returns CORS headers over HTTPS. PostalCodes needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are PostalCodes and US ZipCode free for commercial use?

PostalCodes has unclear commercial terms, and US ZipCode has unclear commercial terms. We track service terms and the data license as separate fields — see the Commercial use and Data license rows above, and confirm both before shipping either in a paid product.