X509

wikipedia:X.509 is a standard defining the format of public key certificates.

Cloudflare certinfo: https://github.com/cloudflare/cfssl/blob/master/certinfo/certinfo.go

openssl x509 -inform pem -noout -text
keytool -printcert -file certificate.pem

openssl x509 -req 

openssl s_client -showcerts -connect YOUR_DOMAIN.COM:443 </dev/null 2>/dev/null | openssl x509 -outform PEM > MY_CERTFILE.pem 

Error response from daemon: Get https://URL/: x509: certificate signed by unknown authority

See also

• X.509, ASN.1, openssl x509, .pem, der, PFX, PKCS, SAN, openssl x509, CSR
• X.509, ASN.1, openssl x509, .pem, der, PFX, PKCS, SAN, openssl x509, CSR
• Public key cryptography, private key, public key, key length, ssh-keygen, ssh-keyscan, Root certificate, KEX, Generate a key
• HTTP, HTTP client, HTTP/1.1, HTTP/2, HTTP/3, HTTPS, HSTS CSR, TLS, SSL, openSSL, WebSockets, WebRTC, ssl_certificate QUIC, HPKP, CT, List of HTTP status codes, URL redirection, Content-type:, Webhook, HTTP headers, --insecure, Axios HTTP client, HTTP cookies, HTTP ETag, Hypertext Transfer Protocol -- HTTP/1.1
• CA, Root Certificates, FreeIPA, PKI, OpenCA, Wildcard certificate, certtool, certbot (Let's Encrypt), certinfo (Cloudflare), ACME, Boulder, cfssl (Cloudflare), Public key certificate, public key, TLS and X.509, OCSP, Subject Alternative Name (SAN), openssl ca, Self signed certificate, CSR, keytool, ACM, KMS, aws acm, IdenTrust, multirootca, cert-manager, ca_cert_identifier

https://prefetch.net/blog/2019/12/10/converting-x509-certificates-to-json-objects/