PEM ↔ DER Converter
Convert between PEM (base64-armoured) and DER (raw) for certificates, CSRs, and public / private keys. Multi-block PEM bundles are recognised; the first block is exposed for conversion. Drag-and-drop or pick a .pem / .der / .crt / .cer / .key file.
Input
Result
Paste, drop, or pick a file to convert.
All conversion happens in your browser. No certificate or key bytes are sent to any server.
PEM and DER in one line
DER is the raw binary encoding of an ASN.1 structure (per X.690). PEM is just DER inside -----BEGIN/END LABEL----- base64 armour, defined by RFC 7468. The label tells you what is inside (CERTIFICATE, CERTIFICATE REQUEST, PRIVATE KEY, etc.) — but the content is the same DER bytes either way.
Spec
RFC 7468 (PEM textual encodings) and X.690 (BER/DER).