PEM Certificate Decoder

Paste a PEM-encoded certificate to decode and inspect its subject, issuer, validity dates, SANs, fingerprints, and signature algorithm. 100% client-side.

Features

• Subject and issuer field extraction
• Validity start and expiry dates
• SHA-256 and SHA-1 fingerprints
• Signature algorithm detection
• Subject Alternative Names listing
• 100% client-side

Frequently Asked Questions

How do I decode a PEM certificate?

Paste your PEM text (including the -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- markers) into the input field. The decoder parses it instantly and shows the subject, issuer, validity, SANs, fingerprint, and signature algorithm.

What signature algorithms are detected?

All common X.509 algorithms are recognized: RSA (SHA-256/384/512 with RSA), ECDSA (SHA-256/384 with ECDSA), and legacy SHA-1 with RSA. Weak algorithms like SHA-1 and MD5 are flagged.