PEM Certificate Decoder

Decode a PEM-encoded X.509 certificate to inspect its subject, issuer, validity dates, and public key details locally in your browser.

Decodes only — does not verify

This reads the certificate's structure and displays its fields. It does not check the signature, validate the certificate chain, confirm revocation status, or otherwise establish trust. Use your browser, OS certificate store, or a dedicated tool like OpenSSL for actual trust verification.

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About PEM Certificate Decoder

PEM Certificate Decoder reads a PEM-encoded X.509 certificate and displays its subject, issuer, validity dates, serial number, and public key/signature algorithms, entirely in your browser.

How to use PEM Certificate Decoder

  1. Paste a PEM certificate, including the -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- lines.
  2. Click Decode certificate.
  3. Review the subject, issuer, validity dates, and algorithm fields.
  4. Check the serial number and version if you need to cross-reference the certificate.

Examples

Input: a PEM block for a TLS certificate Output: Subject: CN=example.com, Issuer: CN=Example CA, Valid from/until dates, Public key algorithm: RSA.

FAQ

Does this verify the certificate is trusted or valid?

No. It only decodes and displays the certificate's fields. It does not check the signature, chain of trust, or revocation status.

Does this support private keys or certificate chains with multiple certificates?

No, it decodes a single X.509 certificate block only, not private keys or certificate bundles.

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