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ES·pera API vs NPPES

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

APIES·pera APIDYING37NPPESHEALTHY94
Uptime · 30d
Uptime · 90d0.0%100%
Uptime · 30d0.0%100%
P50 · ms—366
P95 · ms—2071
Authnonenone
CORSnono
HTTPSyesyes
Card requirednono
Commercial useunclearyes
Data licenseU.S. Government (public NPI data)
Free tierFree — no key required
Rate limitUnpublished
In directory since2026-09-212026-07-05
operationalpartialdownno data

ES·pera API vs NPPES: common questions

Which is more reliable, ES·pera API or NPPES?

On our scheduled checks, NPPES leads on measured uptime — ES·pera API at 0.0% versus NPPES at 100% 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 ES·pera API and NPPES need an API key?

Neither needs a paid key — ES·pera API is callable with no signup, and NPPES is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call ES·pera API and NPPES from the browser?

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

Are ES·pera API and NPPES free for commercial use?

ES·pera API has unclear commercial terms, and NPPES allows commercial use on its free tier. 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.