https://hostname.example.com:2087/cpsess##########/json-api/cpanel?cpanel_jsonapi_user=user&cpanel_jsonapi_apiversion=2&cpanel_jsonapi_module=Encoding&cpanel_jsonapi_func=guess_file&file=public_html/index.html

$cpanel = new CPANEL(); // Connect to cPanel - only do this once.
 
// Retrieve encoding for
$get_encodings = $cpanel->api2(
    'Encoding', 'guess_file', 
		array (
			'file'				=> 'public_html/index.html',

    ) 
);

my $cpliveapi = Cpanel::LiveAPI->new(); # Connect to cPanel - only do this once.
 
# Uninstall DomainKeys on example.com.
my $get_encodings = $cpliveapi->api2(
    'Encoding', 'guess_file'
		{
		'file' 				=> 'public_html/index.html'
		}
  );

cpapi2 --user=username Encoding guess_file file=public_html%2Findex.html

{
  "cpanelresult": {
    "apiversion": 2,
    "func": "guess_file",
    "data": [
      {
        "file": /home/user/public_html/index.html,
        "encoding": "us-ascii"
      }
    ],
    "event": {
      "result": 1
    },
    "module": "Encoding"
  }
}