X.509 Certificate Viewer
Reads a PEM or DER-encoded X.509 certificate and decodes its subject, issuer, validity dates, public key info and Subject Alternative Names directly from the ASN.1 structure.
Nothing here leaves your browser. Certificates are public information by design, but this promise holds regardless.
Drop a .pem, .crt, .cer or .der file here, or click to choose one
Works entirely offline in your browser. Nothing is uploaded.
Decodes the certificate’s ASN.1/DER structure directly — it doesn’t verify the signature or check it against any trust store, so “valid” here means “within its validity dates,” not “trusted.”