Extract certificate from a domain

Published on July 6, 2025

To extract the certificate use:

openssl s_client -showcerts -servername humberto.io -connect humberto.io:443 </dev/null 2>/dev/null

If your target is not using SNI you don’t need to use the -servername <fqdn> option.

Then you can pipe it with other OpenSSL commands to extract information in the format that you need.

To extract PEM formatted cert:

| openssl x509 -outform PEM

To extract the public key:

| openssl x509 -pubkey -noout

To extract the Fingerprint:

| openssl x509 -fingerprint -noout

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