Guide

Generate a CSR online.

A CSR is not a certificate. It is a signed request that carries your public key and identity. A CA turns it into a trusted cert.

Never send the private key

The CA only needs the .csr. If a site asks you to upload the .key, leave. SelfSignedCert's CSR generator creates both in this tab and never posts them.

After the CA replies

Pair the issued .crt with the same key you generated here. If you lost the key, the cert is useless. Decode a CSR first with the CSR decoder if you want to check the subject.