Openssl s client -showcerts

openssl s_client -showcerts -connect YOUR_DOMAIN.COM:443

openssl s_client -showcerts 

openssl s_client -showcerts  https://google.com
40B78119DD7F0000:error:10080002:BIO routines:BIO_lookup_ex:system lib:../crypto/bio/bio_addr.c:738:Servname not supported for ai_socktype connect:errno=0

See also

• openssl, openssl s_client
• TLS, mTLS: OpenSSL, LibreSSL, BoringSSL, WolfSSL, X.509, .pem, SNI, CT, OCSP, Mbed TLS, ALPN, your connection is not private, SSL Certificate Checker, Wildcard certificate, JA3 fingerprint, sslcan, TLS inspection