Here you can match the Certificates with a private key or CSR.
When handling multiple certificates or keys, you can accidentally end up configuring the server or load balancer with a mismatching key or certificate. It's good, you can match before applying.
If you don't prefer to match online, you can perform the same from the command line using openssl command.
First extract modulus of X.509 certificates, RSA private keys, or Certificate Signing Requests (CSRs).
$ openssl x509 -noout -modulus -in certificate.pem | openssl sha256
$ openssl rsa -noout -modulus -in private_key.pem | openssl sha256
$ openssl req -noout -modulus -in csr.pem | openssl sha256
If the hashes match, then those two files match.