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ClickSend REST API v3 vs PostalCodes

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

APIClickSend REST API v3HEALTHY96PostalCodesHEALTHY84
Uptime · 30d
Uptime · 90d100%99.02%
Uptime · 30d100%98.3%
P50 · ms3241030
P95 · ms10352594
AuthapiKeynone
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree tier — API key requiredFree — limits not published
Rate limit6000 req/window · 5999 remaining · resets 1Unpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

ClickSend REST API v3 vs PostalCodes: common questions

Which is more reliable, ClickSend REST API v3 or PostalCodes?

On our scheduled checks, ClickSend REST API v3 leads on measured uptime — ClickSend REST API v3 at 100% versus PostalCodes at 99.02% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.

Which is faster, ClickSend REST API v3 or PostalCodes?

ClickSend REST API v3 has the lower median latency in our checks — ClickSend REST API v3 responds in 324 ms versus PostalCodes at 1030 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 ClickSend REST API v3 and PostalCodes need an API key?

PostalCodes needs no key, while ClickSend REST API v3 requires a free API key. If you want to start calling without signup, reach for PostalCodes first.

Can I call ClickSend REST API v3 and PostalCodes from the browser?

Only ClickSend REST API v3 is browser-friendly — it returns CORS headers over HTTPS. PostalCodes needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are ClickSend REST API v3 and PostalCodes free for commercial use?

ClickSend REST API v3 has unclear commercial terms, and PostalCodes 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.