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InternetDB API vs MailboxValidator Free Email Checker

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

APIInternetDB APIHEALTHY99MailboxValidator Free Email CheckerHEALTHY94
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms133527
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?

Both are neck-and-neck — InternetDB API and MailboxValidator Free Email Checker each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.

Which is faster, InternetDB API or MailboxValidator Free Email Checker?

InternetDB API has the lower median latency in our checks — InternetDB API responds in 133 ms versus MailboxValidator Free Email Checker at 527 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.