Convert a binary DER certificate into a Base64 PEM encoded .cer file. Everything runs in your browser.
Select a binary DER encoded certificate file. The PEM .cer output appears below.
DER is the raw binary ASN.1 encoding of an X.509 certificate. A .cer file in PEM form stores the same certificate as Base64 text between -----BEGIN CERTIFICATE----- markers. This tool Base64-encodes the DER bytes and wraps them with the correct headers - the browser equivalent of openssl x509 -inform DER -in cert.der -out cert.cer.
Convert and package keys for SSH, TLS, and keystore workflows.