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OpenHolidays API vs The SMS Works API

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

APIOpenHolidays APIHEALTHY94The SMS Works APIHEALTHY94
Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms533518
P95 · ms39201101
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

OpenHolidays API vs The SMS Works API: common questions

Which is more reliable, OpenHolidays API or The SMS Works API?

Both are neck-and-neck — OpenHolidays API and The SMS Works API each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.

Which is faster, OpenHolidays API or The SMS Works API?

The SMS Works API has the lower median latency in our checks — OpenHolidays API responds in 533 ms versus The SMS Works API at 518 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.

Do OpenHolidays API and The SMS Works API need an API key?

OpenHolidays API needs no key, while The SMS Works API requires a free API key. If you want to start calling without signup, reach for OpenHolidays API first.

Can I call OpenHolidays API and The SMS Works API from the browser?

Yes — both OpenHolidays API 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 OpenHolidays API and The SMS Works API free for commercial use?

OpenHolidays API 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.