SSL Certificate Parser

SSL Certificate Parser decodes PEM-encoded X.509 SSL/TLS certificates and displays every field in a structured, human-readable format including subject distinguished name (DN), issuer DN, validity period (not-before and not-after dates), public key algorithm and key size, serial number, signature algorithm, and all X.509 v3 extensions. Extensions displayed include Subject Alternative Names (SANs), Key Usage, Extended Key Usage, Authority Information Access (AIA), CRL Distribution Points, and Basic Constraints. DevOps engineers and security professionals use this tool to quickly audit certificates without installing OpenSSL or running command-line tools.

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How to Use

Paste your PEM-encoded certificate, the block of text between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----, into the input area and click Parse. The tool decodes the DER content and displays each field in a labeled structured view. Certificate chain parsing is supported; paste multiple concatenated PEM certificates to inspect each one in the chain. Copy individual field values or the full parsed output for inclusion in security audit reports or runbook documentation.

Common Use Cases

• •Checking SSL certificate expiration dates (not-after field) well before renewal deadlines to prevent unexpected HTTPS outages
• •Verifying that Subject Alternative Names (SANs) include all required hostnames and wildcard domains before certificate deployment
• •Inspecting certificate chain issuer fields and AIA URLs to diagnose incomplete chain TLS handshake failures in server configurations
• •Auditing certificate key sizes and signature algorithms (SHA-256, ECDSA P-256) for compliance with security policy requirements
• •Comparing subject and extension fields between staging and production certificates to detect misconfiguration before a deployment

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