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PostcodeData.nl vs Proweblook IP Checker

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

APIPostcodeData.nlHEALTHY91Proweblook IP CheckerREACHABLE100
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms69256
P95 · ms1989232
AuthnoneapiKey
CORSyesyes
HTTPSnoyes
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

PostcodeData.nl vs Proweblook IP Checker: common questions

Which is more reliable, PostcodeData.nl or Proweblook IP Checker?

Both are neck-and-neck — PostcodeData.nl and Proweblook IP Checker 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, PostcodeData.nl or Proweblook IP Checker?

Proweblook IP Checker has the lower median latency in our checks — PostcodeData.nl responds in 692 ms versus Proweblook IP Checker at 56 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 PostcodeData.nl and Proweblook IP Checker need an API key?

PostcodeData.nl needs no key, while Proweblook IP Checker requires a free API key. If you want to start calling without signup, reach for PostcodeData.nl first.

Can I call PostcodeData.nl and Proweblook IP Checker from the browser?

Only Proweblook IP Checker is browser-friendly — it returns CORS headers over HTTPS. PostcodeData.nl needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are PostcodeData.nl and Proweblook IP Checker free for commercial use?

PostcodeData.nl has unclear commercial terms, and Proweblook IP Checker 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.