caldays vs mailboxlayer
Same instrument, two spec sheets — measured, not claimed.
caldays vs mailboxlayer: common questions
Which is more reliable, caldays or mailboxlayer?
Both are neck-and-neck — caldays and mailboxlayer each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.
Which is faster, caldays or mailboxlayer?
caldays has the lower median latency in our checks — caldays responds in 149 ms versus mailboxlayer at 316 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 mailboxlayer need an API key?
caldays needs no key, while mailboxlayer requires a free API key. If you want to start calling without signup, reach for caldays first.
Can I call caldays and mailboxlayer from the browser?
Only caldays is browser-friendly — it returns CORS headers over HTTPS. mailboxlayer needs a server-side call or proxy, so factor that into which one fits a front-end project.
Are caldays and mailboxlayer free for commercial use?
caldays has unclear commercial terms, and mailboxlayer 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.