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US ZipCode vs What3Words

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

APIUS ZipCodeNEW—What3WordsNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree tier — key may be required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

US ZipCode vs What3Words: common questions

Which is more reliable, US ZipCode or What3Words?

On our scheduled checks, What3Words leads on measured uptime — US ZipCode at —% versus What3Words 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 US ZipCode and What3Words need an API key?

Both ask you to authenticate — US ZipCode uses an API key and What3Words uses an API key. Each key is free to obtain; the Auth and Card-required rows above spell out the signup terms.

Can I call US ZipCode and What3Words from the browser?

Only US ZipCode is browser-friendly — it returns CORS headers over HTTPS. What3Words needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are US ZipCode and What3Words free for commercial use?

US ZipCode has unclear commercial terms, and What3Words 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.