Parses X.509 digital certificates and displays all fields: subject, issuer, validity period, public key, extensions, signature algorithm, and more. Accepts PEM or DER-encoded certificates.
Inputs
Certificate: X.509 certificate in PEM format (-----BEGIN CERTIFICATE-----) or DER hex.
Tips
X.509 certificates are the basis of TLS/SSL, code signing, and PKI systems.
Key extensions to look for: Subject Alternative Names, Key Usage, Basic Constraints.
The serial number and fingerprint uniquely identify a certificate.