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mail.tm vs Slack

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

APImail.tmHEALTHY82SlackHEALTHY97
Uptime · 30d
Uptime · 90d84.3%100%
Uptime · 30d75.0%100%
P50 · ms709324
P95 · ms2351808
AuthnoneapiKey
CORSnoyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — temporary mailboxesFree tier — API key required
Rate limitRate limited (429 on exceed); exact policy per docs.mail.tmUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

mail.tm vs Slack: common questions

Which is more reliable, mail.tm or Slack?

On our scheduled checks, Slack leads on measured uptime — mail.tm at 84.3% versus Slack at 100% 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, mail.tm or Slack?

Slack has the lower median latency in our checks — mail.tm responds in 709 ms versus Slack at 324 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 mail.tm and Slack need an API key?

mail.tm needs no key, while Slack requires a free API key. If you want to start calling without signup, reach for mail.tm first.

Can I call mail.tm and Slack from the browser?

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

Are mail.tm and Slack free for commercial use?

mail.tm has unclear commercial terms, and Slack 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.