Guerrilla Mail vs The Calendar

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

Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms
P95 · ms
Authnonenone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified (US federal list per 5 U.S.C. § 6103)
Free tierFree — limits not publishedFree, no auth (per site)
Rate limitUnpublishedNone stated (site advertises no rate limit)
In directory since2026-07-052026-07-05
operationalpartialdownno data

Guerrilla Mail vs The Calendar: common questions

Which is more reliable, Guerrilla Mail or The Calendar?

On our scheduled checks, The Calendar leads on measured uptime — Guerrilla Mail 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 Guerrilla Mail and The Calendar need an API key?

Neither needs a paid key — Guerrilla Mail is callable with no signup, and The Calendar is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call Guerrilla Mail and The Calendar from the browser?

Yes — both Guerrilla Mail 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 Guerrilla Mail and The Calendar free for commercial use?

Guerrilla Mail 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.