SSL Certificate Decoder

The SSL certificate decoder parses X.509 certificates to expose critical security and configuration details in a structured format. It accepts certificate_pem input (PEM or DER) or a domain for automatic certificate retrieval and chain analysis. The tool outputs a machine- and human-readable summary including subject, issuer, validity window, serial number, signature algorithm, public key algorithm and length, SANs, and cryptographic fingerprints. It can also expand the certificate chain, report basic constraints and key usage, and present a compact chain overview for quick trust assessment. The approach aligns with RFC 5280 conventions and uses UTF-8 for any non-ASCII fields, ensuring interoperability with typical TLS deployments. The decoder is designed for security teams, DevOps, site owners, and auditors who need fast, repeatable certificate intel without manual DER/PEM parsing or external tooling. In practice, users provide certificate_pem or domain; the tool internally decodes the DER representation, maps fields to a consistent schema, and formats dates in ISO 8601. Outputs include a primary certificate object and, when requested, a chain_summary with issuer names and validity windows. The value proposition lies in speed, accuracy, and automation: it reduces time spent reading raw certificate blobs, supports automated pipelines, and yields data that can feed compliance checks or risk scoring. Common use cases include validating new certs during deployment, auditing expiring certificates, and comparing domain configurations across environments. Core features and capabilities include robust PEM/DER decoding, support for multiple SAN entries, SHA-256 and SHA-1 fingerprints, and optional chain visibility. The tool focuses on developers and operators who need deterministic, exportable certificate data for dashboards, alerts, and documentation.