MailCheck.ai vs The Calendar
Same instrument, two spec sheets — measured, not claimed.
MailCheck.ai vs The Calendar: common questions
Which is more reliable, MailCheck.ai or The Calendar?
On our scheduled checks, The Calendar leads on measured uptime — MailCheck.ai at 93.1% versus The Calendar at 100% 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, MailCheck.ai or The Calendar?
MailCheck.ai has the lower median latency in our checks — MailCheck.ai responds in 272 ms versus The Calendar at 588 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 MailCheck.ai and The Calendar need an API key?
Neither needs a paid key — MailCheck.ai 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 MailCheck.ai and The Calendar from the browser?
Yes — both MailCheck.ai 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 MailCheck.ai and The Calendar free for commercial use?
MailCheck.ai 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.