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PostStack vs The SMS Works API

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

APIPostStackNEW—The SMS Works APINEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSnoyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — key may be requiredFree tier — API key required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

PostStack vs The SMS Works API: common questions

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

On our scheduled checks, The SMS Works API leads on measured uptime — PostStack 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 PostStack and The SMS Works API need an API key?

Both ask you to authenticate — PostStack uses an API key and The SMS Works API uses an API key. Each key is free to obtain; the Auth and Card-required rows above spell out the signup terms.

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

Only The SMS Works API is browser-friendly — it returns CORS headers over HTTPS. PostStack needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are PostStack and The SMS Works API free for commercial use?

PostStack 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.