F1 API vs NPPES
Same instrument, two spec sheets — measured, not claimed.
F1 API vs NPPES: common questions
Which is more reliable, F1 API or NPPES?
On our scheduled checks, NPPES leads on measured uptime — F1 API at 45.1% 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.
Which is faster, F1 API or NPPES?
NPPES has the lower median latency in our checks — F1 API responds in 4909 ms versus NPPES at 910 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 F1 API and NPPES need an API key?
Neither needs a paid key — F1 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 F1 API and NPPES from the browser?
Only F1 API is browser-friendly — it returns CORS headers over HTTPS. NPPES needs a server-side call or proxy, so factor that into which one fits a front-end project.
Are F1 API and NPPES free for commercial use?
F1 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.