caldays vs Guerrilla Mail
Same instrument, two spec sheets — measured, not claimed.
caldays vs Guerrilla Mail: common questions
Which is more reliable, caldays or Guerrilla Mail?
On our scheduled checks, Guerrilla Mail leads on measured uptime — caldays 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 caldays and Guerrilla Mail need an API key?
Neither needs a paid key — caldays is callable with no signup, and Guerrilla Mail is callable with no signup. Both are quick to prototype with; rate limits still apply.
Can I call caldays and Guerrilla Mail from the browser?
Yes — both caldays 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 caldays and Guerrilla Mail free for commercial use?
caldays 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.