SSL Certificate Decoder
Inspect and decode PEM-encoded X.509 certificates, view validity periods, subject alternative names (SAN), and issuer details instantly.
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SSL / TLS Reference
1. X.509 Format & PEM
Certificates are encoded in Base64 DER format wrapped with header and footer boundary markers (`-----BEGIN CERTIFICATE-----`).
2. Subject Alternative Names (SAN)
Modern browsers require SAN extensions to validate multiple subdomains and domain variations under a single certificate.
Frequently Asked Questions (FAQ)
No. Public certificates contain only public keys and metadata. Never paste your private key (`-----BEGIN PRIVATE KEY-----`) into online decoders.
Root certificates are pre-installed in client operating systems and browsers, while intermediate certificates act as stepping stones issued by the root to sign end-entity server certificates.
Lookups and structure parsing execute locally in your browser to inspect attribute blocks and structural properties instantly.