DevToolsHub Logo

SSL Certificate Decoder

Decode and analyze PEM/X.509 SSL certificates.

Free online tool. No signup required. All processing runs in your browser.

About this tool

Paste a PEM certificate (or upload a .crt/.pem file) to see subject, issuer, validity dates, SANs, and other fields. No data is sent to a server.

What is SSL Certificate Decoder?

SSL/TLS certificates are X.509 documents that bind a public key to a domain and identity. PEM is a common text format (Base64) for storing certificates.

How to use SSL Certificate Decoder

  1. Paste PEM content or upload a certificate file.
  2. View decoded subject, issuer, and validity.
  3. Check extensions (SANs, key usage) if needed.

Examples

Example input

-----BEGIN CERTIFICATE-----
MIID...
-----END CERTIFICATE-----

Example output

Subject: CN=example.com, Issuer: CN=CA, Valid: 2024-01-01 to 2025-01-01

FAQ

What is PEM?
PEM (Privacy-Enhanced Mail) is a Base64-encoded format with -----BEGIN CERTIFICATE----- / -----END CERTIFICATE----- boundaries.
Can I decode a chain?
Paste the first certificate; some tools support multiple PEM blocks for a chain.

Related tools