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