TLS Configuration
Inspect TLS protocols, cipher suites, handshake behavior and HTTPS negotiation.
Enter a hostname without https://. We handle the TLS connection.
Enter a hostname to inspect TLS configuration
Protocol versions, cipher suite, ALPN, SNI, and handshake timing appear here.
TLS Configuration connects to a hostname over HTTPS and inspects the negotiation itself, separately from the certificate it presents: which protocol versions the server accepts, the cipher suite and ALPN protocol it actually negotiates, whether it requires SNI to select the right certificate, and how long the TCP connection and TLS handshake each take.
TLS 1.3 and TLS 1.2 are tested directly by forcing a connection to exactly that version. TLS 1.1 and TLS 1.0 are tested the same way where the check server's own TLS stack is able to attempt them at all — modern server environments frequently disable those versions at the operating system level, in which case the result is reported as unable to test rather than guessed at.
This isn't a replacement for SSL Certificate Checker's own certificate detail — chain inspection, every covered subdomain, and signature algorithm still live there. This tool covers the negotiation layer around the certificate: what a real client connecting to this server would actually get.