To view the HTTP headers of any URL all you need to do is run the following with cURL:

$ curl -I https://example.com

The response should look something like this:

HTTP/2 200
accept-ranges: bytes
cache-control: max-age=604800
...
x-cache: HIT
content-length: 1270

If your URL has query strings then you will need to add double quotes:

curl -I "https://example.com?query=string&foo=bar"