There's a README file in the letsencrypt/live/servername directory with some useful details. cat README This directory contains your keys and certificates. `privkey.pem`  : the private key for your certificate. `fullchain.pem`: the certificate file used in most server software. `chain.pem`    : used for OCSP stapling in Nginx >=1.3.7. `cert.pem`     : will break many server configurations, and should not be used                  without reading further documentation (see l