There are a couple of steps required to force a browser to save/download content instead of displaying it in the browser window.
X-Download-Options: noopen
X-Content-Type-Options:nosniff
Content-Disposition: attachment; filename=example.txt
Content-Type: text/plain
NOTE: MSIE also supports a poorly documented proprietary META tag…
<meta name="DownloadOptions" content="noopen|nosave" />
REFERENCES:
