Tlsscope
The TLS certificate chain, read directly from the wire
Paste a hostname. Tlsscope opens a TLS connection, reads the certificate chain the server sends on the wire, and reports the expiry date, issuer, covered hostnames, and whether every intermediate was transmitted.
This is not a cached or guessed value. It is what the server actually sent.
Why the chain matters
A certificate can be valid and the site still break, because the server sends the leaf without its intermediate certificate. Desktop browsers cache the missing intermediate from previous visits and paper over the gap. Mobile clients do not. That failure is invisible to anyone checking only the expiry date, and it is the one people lose a weekend to.
Tlsscope reports whether the server sent a complete chain — every intermediate needed to build trust from the leaf to a recognised root — or omitted certificates that will cause some clients to reject the connection.