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BulkSMS JSON REST API vs PostStack

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

APIBulkSMS JSON REST APINEW—PostStackNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
AuthapiKeyapiKey
CORSnono
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree tier — key may be required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

BulkSMS JSON REST API vs PostStack: common questions

Which is more reliable, BulkSMS JSON REST API or PostStack?

On our scheduled checks, PostStack leads on measured uptime — BulkSMS JSON REST API at —% versus PostStack 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 BulkSMS JSON REST API and PostStack need an API key?

Both ask you to authenticate — BulkSMS JSON REST API uses an API key and PostStack 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 BulkSMS JSON REST API and PostStack from the browser?

Neither sends browser-friendly CORS headers reliably, so call BulkSMS JSON REST API and PostStack from a server or proxy rather than client-side. The CORS and HTTPS rows above show exactly what we detected for each.

Are BulkSMS JSON REST API and PostStack free for commercial use?

BulkSMS JSON REST API has unclear commercial terms, and PostStack 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.