Numverify vs Userstack
Same instrument, two spec sheets — measured, not claimed.
Numverify vs Userstack: common questions
Which is more reliable, Numverify or Userstack?
On our scheduled checks, Numverify leads on measured uptime — Numverify at 100% versus Userstack at 99.02% 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, Numverify or Userstack?
Userstack has the lower median latency in our checks — Numverify responds in 449 ms versus Userstack at 443 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 Numverify and Userstack need an API key?
Both ask you to authenticate — Numverify uses an API key and Userstack uses an API key. Each key is free to obtain; the Auth and Card-required rows above spell out the signup terms.
Can I call Numverify and Userstack from the browser?
Only Userstack is browser-friendly — it returns CORS headers over HTTPS. Numverify needs a server-side call or proxy, so factor that into which one fits a front-end project.
Are Numverify and Userstack free for commercial use?
Numverify has unclear commercial terms, and Userstack 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.