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Ducks Unlimited vs PostalCodes

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

APIDucks UnlimitedNEW—PostalCodesNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree — limits not published
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Ducks Unlimited vs PostalCodes: common questions

Which is more reliable, Ducks Unlimited or PostalCodes?

On our scheduled checks, PostalCodes leads on measured uptime — Ducks Unlimited at —% versus PostalCodes 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 Ducks Unlimited and PostalCodes need an API key?

Neither needs a paid key — Ducks Unlimited is callable with no signup, and PostalCodes is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call Ducks Unlimited and PostalCodes from the browser?

Only Ducks Unlimited 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 Ducks Unlimited and PostalCodes free for commercial use?

Ducks Unlimited has unclear commercial terms, and PostalCodes 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.