*.pfx-File: export certificate and key (*.pem / *.key) / *.pfx to *.pem

Download and install OpenSSL

Download for Windows On linux-based systems it should be already installed, if not:
sudo apt install openssl

Export private key

openssl pkcs12 -in filename.pfx -nocerts -out privatekey.pem -nodes

Export certificate

openssl pkcs12 -in filename.pfx -nokeys -out certificate.pem
Remove password from private key
 openssl rsa -in privatekey.pem -out private.key