SSL Checker
Inspect any site's TLS certificate: expiry, issuer, names, chain.
Port 443 unless you specify host:port.
What this page does: it connects to the given host over TLS and reads the certificate the server presents: who it was issued to, who issued it, the validity window with days remaining, the serial number, the signature algorithm, all subject alternative names, and the chain of intermediate certificates. Useful for catching certificates before they expire, verifying a renewal deployed correctly, or checking which names a certificate actually covers.