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PostStack vs Slack

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

APIPostStackNEW—SlackNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSnoyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — key may be requiredFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

PostStack vs Slack: common questions

Which is more reliable, PostStack or Slack?

On our scheduled checks, Slack leads on measured uptime — PostStack at —% versus Slack 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 PostStack and Slack need an API key?

Both ask you to authenticate — PostStack uses an API key and Slack 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 PostStack and Slack from the browser?

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

Are PostStack and Slack free for commercial use?

PostStack 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.