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caldays vs Tumblr

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

APIcaldaysNEW—TumblrREACHABLE—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnoneoauth
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedOAuth — some read routes may be public
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

caldays vs Tumblr: common questions

Which is more reliable, caldays or Tumblr?

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

caldays needs no key, while Tumblr requires OAuth. If you want to start calling without signup, reach for caldays first.

Can I call caldays and Tumblr from the browser?

Yes — both caldays and Tumblr 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 caldays and Tumblr free for commercial use?

caldays has unclear commercial terms, and Tumblr 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.