DecodeEncode
SSL/PEM Certificate Decoder

SSL/PEM Certificate Decoder

Decode and inspect X.509 certificates

Client-sideX.509 / PEMInstant

What is a PEM Certificate?

A PEM (Privacy Enhanced Mail) certificate is a Base64-encoded X.509 certificate enclosed between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- headers. It is the most common format for SSL/TLS certificates used to secure websites and services.

How to Use this Tool
  1. Paste Your Certificate: Copy your PEM-encoded certificate and paste it into the input area.
  2. Click Decode: Press the "Decode Certificate" button to parse and inspect the certificate.
  3. View Details: See the subject, issuer, validity dates, serial number, signature algorithm, public key info, and expiry status.
  4. Copy JSON: Click "Copy JSON" to copy all decoded details as a JSON object.
What Information is Decoded?
  • Subject: The entity the certificate is issued to.
  • Issuer: The Certificate Authority that signed the certificate.
  • Validity: The date range during which the certificate is valid.
  • Serial Number: A unique identifier assigned by the CA.
  • Signature Algorithm: The algorithm used to sign the certificate (e.g., SHA-256 with RSA).
  • Public Key: The type and size of the public key (e.g., RSA 2048-bit).
  • SANs: Subject Alternative Names — additional domains covered by the certificate.
Important Note:

All parsing is done entirely in your browser. Your certificate data never leaves your device. We use the open-source node-forge library for X.509 parsing.

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