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ImprovMX API vs Resend

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

APIImprovMX APIDEAD0ResendDEAD0
Uptime · 30d
Uptime · 90d0.0%0.0%
Uptime · 30d0.0%0.0%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree tier — API key required
Rate limit301 req/window · 300 remaining · resets 1783526520Unpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

ImprovMX API vs Resend: common questions

Which is more reliable, ImprovMX API or Resend?

Both are neck-and-neck — ImprovMX API and Resend each measure 0.0% 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.

Do ImprovMX API and Resend need an API key?

Both ask you to authenticate — ImprovMX API uses an API key and Resend 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 ImprovMX API and Resend from the browser?

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

Are ImprovMX API and Resend free for commercial use?

ImprovMX API has unclear commercial terms, and Resend 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.