Cisco Spark vs Guerrilla Mail

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
Free tierFree tier — API key requiredFree — limits not published
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Cisco Spark vs Guerrilla Mail: common questions

Which is more reliable, Cisco Spark or Guerrilla Mail?

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

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

Can I call Cisco Spark and Guerrilla Mail from the browser?

Yes — both Cisco Spark and Guerrilla Mail 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 Guerrilla Mail free for commercial use?

Cisco Spark has unclear commercial terms, and Guerrilla Mail 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.