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InternetDB API vs MailboxValidator Free Email Checker

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

APIInternetDB APIHEALTHY99MailboxValidator Free Email CheckerHEALTHY96
Uptime · 30d
Uptime · 90d100%99.44%
Uptime · 30d100%98.3%
P50 · ms113248
P95 · ms22601138
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, InternetDB API leads on measured uptime — InternetDB API at 100% versus MailboxValidator Free Email Checker at 99.44% 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, InternetDB API or MailboxValidator Free Email Checker?

InternetDB API has the lower median latency in our checks — InternetDB API responds in 113 ms versus MailboxValidator Free Email Checker at 248 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 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.