About this tool
PEM files are base64-encoded certificates or certificate signing requests wrapped between -----BEGIN and -----END markers. Decoding them reveals the exact names covered by the certificate (SANs), the issuing CA, expiry dates and the signature algorithm, critical for audit trails, renewal planning and incident response. CSR decoding lets you verify the correct details were captured before submission to a CA. Parsing happens server-side in PHP with no data logged or stored; treat this like any PKI review tool and avoid pasting private keys. For live certificate inspection on a running server, use the SSL/TLS Checker.