The Calendar vs Tumblr
Same instrument, two spec sheets — measured, not claimed.
The Calendar vs Tumblr: common questions
Which is more reliable, The Calendar or Tumblr?
On our scheduled checks, Tumblr leads on measured uptime — The Calendar 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 The Calendar and Tumblr need an API key?
The Calendar needs no key, while Tumblr requires OAuth. If you want to start calling without signup, reach for The Calendar first.
Can I call The Calendar and Tumblr from the browser?
Yes — both The Calendar 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 The Calendar and Tumblr free for commercial use?
The Calendar 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.