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IPWhois vs Postcodes.io

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

APIIPWhoisHEALTHY100Postcodes.ioHEALTHY100
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms2333
P95 · ms598328
AuthapiKeynone
CORSyesyes
HTTPSnoyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedService MIT-licensed; postcode data license unverified
Free tierFree tier — API key may be required for productionFree — no key required
Rate limitUnpublishedUnpublished (no key; fair use)
In directory since2026-07-052026-07-05
operationalpartialdownno data

IPWhois vs Postcodes.io: common questions

Which is more reliable, IPWhois or Postcodes.io?

Both are neck-and-neck — IPWhois and Postcodes.io each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.

Which is faster, IPWhois or Postcodes.io?

IPWhois has the lower median latency in our checks — IPWhois responds in 23 ms versus Postcodes.io at 33 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.

Do IPWhois and Postcodes.io need an API key?

Postcodes.io needs no key, while IPWhois requires a free API key. If you want to start calling without signup, reach for Postcodes.io first.

Can I call IPWhois and Postcodes.io from the browser?

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

Are IPWhois and Postcodes.io free for commercial use?

IPWhois 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.