🔒 SSL/TLS Certificate Decoder

Decode and inspect PEM-encoded certificates. Everything runs in your browser.

Paste PEM Certificate

Free SSL/TLS Certificate Decoder

Instantly decode and inspect SSL/TLS certificates in PEM format. View the full subject and issuer details, serial number, validity period with expiration countdown, signature algorithm, public key info, key usage, extended key usage, Subject Alternative Names (SANs), and SHA-1/SHA-256 fingerprints. Supports certificate chains with multiple certificates. All ASN.1 parsing happens directly in your browser using pure JavaScript - your certificates are never sent to any server. Upload a .pem or .crt file or paste the certificate text directly.