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IsItWater vs PostcodeData.nl

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

APIIsItWaterNEW—PostcodeData.nlNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeynone
CORSnoyes
HTTPSyesno
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree — limits not published
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

IsItWater vs PostcodeData.nl: common questions

Which is more reliable, IsItWater or PostcodeData.nl?

On our scheduled checks, PostcodeData.nl leads on measured uptime — IsItWater at —% versus PostcodeData.nl 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 IsItWater and PostcodeData.nl need an API key?

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

Can I call IsItWater and PostcodeData.nl from the browser?

Neither sends browser-friendly CORS headers reliably, so call IsItWater and PostcodeData.nl from a server or proxy rather than client-side. The CORS and HTTPS rows above show exactly what we detected for each.

Are IsItWater and PostcodeData.nl free for commercial use?

IsItWater has unclear commercial terms, and PostcodeData.nl 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.