Parse and print PEM certificate infos:
openssl x509 -in cert.crt -text
Same with DER (read .crl too):
openssl x509 -in cert.crt -inform der -text
Verify a certificate:
openssl verify -CAfile <(cat Intermediate.pem RootCert.pem) UserCert.pem
Download and show info on an online certificate
openssl s_client -showcerts -connect DOMAIN:443 </dev/null 2>/dev/null | openssl x509 -text
Get fingerprint of a certificate
openssl x509 -noout -fingerprint -md5 -inform pem -in [certificate-file.crt]
Remotely check a certificate:
openssl s_client -showcerts -connect www.domain.com:443
Print a PKCS7 certificate:
openssl pkcs7 -inform DER -print_certs -text -in FILE