QuoVadis provides a PKI Widget to help you determine whether a digital certificate matches a Certificate Signing Request (CSR). This is useful when you are managing many digital certificates and lose track of which CSR corresponds to a certificate.
For more information, please see https://pkiwidgets.quovadisglobal.com/scriptgen/default.aspx
As Subscriber Agreements require you to properly protect your private key at all times, we do not provide an online tool to match certificates to private keys. However, you can use OpenSSL to match the modulus of a given private key and certificate. The command is:
openssl rsa -in mykey.key -noout -modulus
openssl x509 -in mycert.crt -noout -modulus