mailboxlayer vs PostStack
Same instrument, two spec sheets — measured, not claimed.
mailboxlayer vs PostStack: common questions
Which is more reliable, mailboxlayer or PostStack?
Both are neck-and-neck — mailboxlayer and PostStack 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, mailboxlayer or PostStack?
mailboxlayer has the lower median latency in our checks — mailboxlayer responds in 316 ms versus PostStack at 1066 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 mailboxlayer and PostStack need an API key?
Both ask you to authenticate — mailboxlayer uses an API key and PostStack uses an API key. Each key is free to obtain; the Auth and Card-required rows above spell out the signup terms.
Can I call mailboxlayer and PostStack from the browser?
Neither sends browser-friendly CORS headers reliably, so call mailboxlayer and PostStack from a server or proxy rather than client-side. The CORS and HTTPS rows above show exactly what we detected for each.
Are mailboxlayer and PostStack free for commercial use?
mailboxlayer has unclear commercial terms, and PostStack 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.