caldays vs MailCheck.ai
Same instrument, two spec sheets — measured, not claimed.
caldays vs MailCheck.ai: common questions
Which is more reliable, caldays or MailCheck.ai?
On our scheduled checks, caldays leads on measured uptime — caldays at 100% versus MailCheck.ai at 93.1% 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, caldays or MailCheck.ai?
caldays has the lower median latency in our checks — caldays responds in 149 ms versus MailCheck.ai at 272 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 caldays and MailCheck.ai need an API key?
Neither needs a paid key — caldays is callable with no signup, and MailCheck.ai is callable with no signup. Both are quick to prototype with; rate limits still apply.
Can I call caldays and MailCheck.ai from the browser?
Yes — both caldays and MailCheck.ai 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 MailCheck.ai free for commercial use?
caldays has unclear commercial terms, and MailCheck.ai 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.