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IP Address API vs Postcodes.io

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

APIIP Address APINEW—Postcodes.ioNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedService MIT-licensed; postcode data license unverified
Free tierFree — limits not publishedFree — no key required
Rate limitUnpublishedUnpublished (no key; fair use)
In directory since2026-07-052026-07-05
operationalpartialdownno data

IP Address API vs Postcodes.io: common questions

Which is more reliable, IP Address API or Postcodes.io?

On our scheduled checks, Postcodes.io leads on measured uptime — IP Address API at —% versus Postcodes.io 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 IP Address API and Postcodes.io need an API key?

Neither needs a paid key — IP Address API is callable with no signup, and Postcodes.io is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call IP Address API and Postcodes.io from the browser?

Yes — both IP Address API and Postcodes.io send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.

Are IP Address API and Postcodes.io free for commercial use?

IP Address API has unclear commercial terms, and Postcodes.io 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.