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Emailvalidation vs PostStack

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

APIEmailvalidationNEW—PostStackNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree tier — key may be required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Emailvalidation vs PostStack: common questions

Which is more reliable, Emailvalidation or PostStack?

On our scheduled checks, PostStack leads on measured uptime — Emailvalidation at —% versus PostStack 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 Emailvalidation and PostStack need an API key?

Both ask you to authenticate — Emailvalidation uses an API key and PostStack 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 Emailvalidation and PostStack from the browser?

Only Emailvalidation is browser-friendly — it returns CORS headers over HTTPS. PostStack needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are Emailvalidation and PostStack free for commercial use?

Emailvalidation has unclear commercial terms, and PostStack 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.