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InternetDB API vs MailboxValidator Free Email Checker

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

APIInternetDB APINEW—MailboxValidator Free Email CheckerNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthnoneapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

InternetDB API vs MailboxValidator Free Email Checker: common questions

Which is more reliable, InternetDB API or MailboxValidator Free Email Checker?

On our scheduled checks, MailboxValidator Free Email Checker leads on measured uptime — InternetDB API at —% versus MailboxValidator Free Email Checker 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 InternetDB API and MailboxValidator Free Email Checker need an API key?

InternetDB API needs no key, while MailboxValidator Free Email Checker requires a free API key. If you want to start calling without signup, reach for InternetDB API first.

Can I call InternetDB API and MailboxValidator Free Email Checker from the browser?

Only InternetDB API is browser-friendly — it returns CORS headers over HTTPS. MailboxValidator Free Email Checker needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are InternetDB API and MailboxValidator Free Email Checker free for commercial use?

InternetDB API has unclear commercial terms, and MailboxValidator Free Email Checker 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.