#certificate

Decode an X.509 certificate (PEM) into readable details — without a live connection. Paste a certificate and get back its subject and issuer (parsed into fields), the validity window with days-until-expiry and an expired flag, the serial number, SHA-1 and SHA-256 fingerprints, the Subject Alternative Names, the public-key type and size, and the CA / self-signed flags. Pure local parsing with no third-party service. Live, nothing stored. 2 endpoints. Built for certificate inspection, CI/CD expiry checks, PKI debugging and audit tooling. Distinct from a live SSL/TLS endpoint checker — this decodes a certificate you already hold.

api.oanor.com/certdecode-api

Check any website's SSL/TLS certificate as an API. Pass a domain and the service performs a live TLS handshake and returns the certificate's subject and issuer, the validity window, the exact number of days until it expires, whether it is currently valid and trusted by a standard CA chain, the negotiated TLS protocol, serial number, SHA-256 fingerprint, key size and the full list of Subject Alternative Names (SANs). A lean expiry endpoint returns a simple ok / expiring_soon / expired status, perfect for uptime and certificate-expiry monitoring, dashboards, CI checks and security tooling. Self-contained — no third-party service. IP addresses and internal hosts are not supported.

api.oanor.com/sslcheck-api