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Namedays Calendar vs Slack

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

APINamedays CalendarNEW—SlackNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthnoneapiKey
CORSyesyes
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

Namedays Calendar vs Slack: common questions

Which is more reliable, Namedays Calendar or Slack?

On our scheduled checks, Slack leads on measured uptime — Namedays Calendar 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 Namedays Calendar and Slack need an API key?

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

Can I call Namedays Calendar and Slack from the browser?

Yes — both Namedays Calendar and Slack send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.

Are Namedays Calendar and Slack free for commercial use?

Namedays Calendar 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.