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Userstack vs Genderize.io

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

APIUserstackUNMONITORED—Genderize.ioNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeynone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredKeyless usage limited (x-rate-limit-limit: 25 observed); 2,500 names/mo with a free key
Rate limitUnpublishedKeyless cap 25 per x-rate-limit-limit header; remaining/reset exposed in response headers
In directory since2026-07-052026-07-05
operationalpartialdownno data

Userstack vs Genderize.io: common questions

Which is more reliable, Userstack or Genderize.io?

Only Genderize.io is on our probe schedule so far (—% uptime over 90 days). The other is catalogued but not yet live-checked, so we can't compare measured reliability head-to-head — check the uncovered API's own status page for now.

Do Userstack and Genderize.io need an API key?

Genderize.io needs no key, while Userstack requires a free API key. If you want to start calling without signup, reach for Genderize.io first.

Can I call Userstack and Genderize.io from the browser?

Yes — both Userstack and Genderize.io 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 Userstack and Genderize.io free for commercial use?

Userstack has unclear commercial terms, and Genderize.io 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.