Cisco Spark vs The Calendar

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

Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms
P95 · ms
AuthapiKeynone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified (US federal list per 5 U.S.C. § 6103)
Free tierFree tier — API key requiredFree, no auth (per site)
Rate limitUnpublishedNone stated (site advertises no rate limit)
In directory since2026-07-052026-07-05
operationalpartialdownno data

Cisco Spark vs The Calendar: common questions

Which is more reliable, Cisco Spark or The Calendar?

On our scheduled checks, The Calendar leads on measured uptime — Cisco Spark at —% versus The Calendar 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 Cisco Spark and The Calendar need an API key?

The Calendar needs no key, while Cisco Spark requires a free API key. If you want to start calling without signup, reach for The Calendar first.

Can I call Cisco Spark and The Calendar from the browser?

Yes — both Cisco Spark and The Calendar 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 Cisco Spark and The Calendar free for commercial use?

Cisco Spark has unclear commercial terms, and The Calendar 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.