This Javascript will print out response headers to the console.

gistfile1.js

// https://github.com/bgrins/devtools-snippets
// Print out response headers for current URL

(function() {

var request=new XMLHttpRequest();
request.open('HEAD',window.location,false);
request.send(null);

var headers = request.getAllResponseHeaders();
var tab = headers.split("\n").map(function(h) {
	return { "Key": h.split(": ")[0], "Value": h.split(": ")[1] }
}).filter(function(h) { return h.Value !== undefined; });

console.group("Request Headers");
console.log(headers);
console.table(tab);
console.groupEnd("Request Headers");

})();