HTTP Headers
https://en.wikipedia.org/wiki/List_of_HTTP_header_fields
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers
Check headers security
https://observatory.mozilla.org
https://pentest-tools.com/website-vulnerability-scanning/website-scanner
Content-Type
The media type.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type