=== HTTP code : 200 ===

Response headers
================
HTTP/1.1 200 OK
Date: Mon, 29 Jul 2019 00:08:19 GMT
Server: Apache
Last-Modified: Thu, 09 Aug 2018 17:11:10 GMT
ETag: &quot;9c413-57303b6b30cf5&quot;
Accept-Ranges: bytes
Content-Length: 640019
Connection: close
Content-Type: application/pdf

Request headers
================
HEAD /wp-content/uploads/2018/08/SSDP-FY17-Public-Disclosure-Copy-Form-990.pdf HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36
Host: ssdp.org
Accept: */*
Referer: https://ssdp.org
Connection: close


Link is valid.