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Callook.info vs WhoisXML API Email Verification API

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

APICallook.infoNEW—WhoisXML API Email Verification APINEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthnoneapiKey
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverified (data from public FCC ULS records)Unverified
Free tierFree — limits not publishedFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Callook.info vs WhoisXML API Email Verification API: common questions

Which is more reliable, Callook.info or WhoisXML API Email Verification API?

On our scheduled checks, WhoisXML API Email Verification API leads on measured uptime — Callook.info at —% versus WhoisXML API Email Verification API 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 Callook.info and WhoisXML API Email Verification API need an API key?

Callook.info needs no key, while WhoisXML API Email Verification API requires a free API key. If you want to start calling without signup, reach for Callook.info first.

Can I call Callook.info and WhoisXML API Email Verification API from the browser?

Yes — both Callook.info and WhoisXML API Email Verification API 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 Callook.info and WhoisXML API Email Verification API free for commercial use?

Callook.info has unclear commercial terms, and WhoisXML API Email Verification API 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.