X-Frame-Options X-Frame-Options tells the browser whether you want to allow your site to be framed or not. By preventing a browser from framing your site you can defend against attacks like clickjacking.

Expect-CT Expect-CT allows a site to determine if they are ready for the upcoming Chrome requirements and/or enforce their CT policy.

Strict-Transport-Security HTTP Strict Transport Security is an excellent feature to support on your site and strengthens your implementation of TLS by getting the User Agent to enforce the use of HTTPS.

X-Content-Type-Options X-Content-Type-Options stops a browser from trying to MIME-sniff the content type and forces it to stick with the declared content-type. The only valid value for this header is "X-Content-Type-Options: nosniff".