SSL Certificate Decoder & X.509 Viewer | iN2 Tools

Decode PEM-encoded X.509 certificates to view issuer, subject, validity ranges, and public key specs.

SSL/TLS X.509 Certificate Decoder & Inspector

Decode PEM-encoded X.509 SSL/TLS certificates. Inspect Subject Alternative Names (SANs), expiration dates, issuer authority, public key algorithms (RSA/ECDSA), and certificate extensions.

SSL Certificate Decoder

Paste a PEM-encoded X.509 certificate below to decode its metadata, validity dates, subject alternative names, and public key cryptography.

Understanding X.509 SSL/TLS Certificates (RFC 5280)

X.509 is the standard ITU-T format defined in RFC 5280 for public key certificates used in Transport Layer Security (TLS/SSL) web encryption.

Key Certificate Fields

  • Subject Alternative Name (SAN): Defines all hostnames and wildcard subnets secured by the certificate.
  • Validity Period (NotBefore / NotAfter): Standard TLS certificates have a maximum lifetime of 398 days.
  • Key Algorithm: RSA 2048/4096-bit or Elliptic Curve Cryptography (ECDSA P-256 / P-384).
  • Certificate Authority (CA): The trusted root issuer that cryptographically signed the certificate chain.

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