Force Browser to Download File Instead of Opening It

How to force a Download File prompt instead of displaying it in-browser with HTML?

This is something that you cannot absolutely control with HTML itself.

If the user is having a browser with PDF reading capabilities (or a plugin) and the corresponding settings to open PDF files in-browser, the PDF will open like that.

The PDF opens in a new tab simple because of your target="_blank", which has nothing to do with a download prompt.

If you are using HTML5 you can use the download attribute:

<a href="sample.pdf" download="sample.pdf">Download</a>

If you have a back-end service which you can control or you feel like fiddling with your Web Server, you can always look for setting the right Content-Disposition. See this SO question for some nice discussion on Content-Disposition.

Force browser to download file instead of opening it

You just need to make sure to send these headers:

Content-Disposition: attachment; filename=song.mp3;
Content-Type: application/octet-stream
Content-Transfer-Encoding: binary

The send_file method does it for you:

get '/:file' do |file|
  file = File.join('/some/path', file)
  send_file(file, :disposition => 'attachment', :filename => File.basename(file))
end

Can I force the browser to download the PDF file instead of opening it?

If you want the browser to download as attachment, you need to say so using the Content-Disposition header field. See http://greenbytes.de/tech/webdav/rfc6266.html#disposition.type, disposition type "attachment".

(HTML) Download a PDF file instead of opening them in browser when clicked

There is now the HTML 5 download attribute that can handle this.

I agree, and think Sarim's answer is good (it probably should be the chosen answer if the OP ever returns). However, this answer is still the reliable way to handle it (as Yiğit Yener's answer points out and--oddly--people agree with). While the download attribute has gained support, it's still spotty:

http://caniuse.com/#feat=download

force browser to download a file instead viewing it

You need to force file download in your server-side script:

Here is a PHP example:

$file = "path/to/my-file.pdf";

header("Cache-Control: public");
header("Content-Description: File Transfer");
header("Content-Disposition: attachment; filename=$file");
header("Content-Type: application/pdf");
header("Content-Transfer-Encoding: binary");

Force browser to download PDF document instead of opening it

You should look at the "Content-Disposition" header; for example setting "Content-Disposition" to "attachment; filename=foo.pdf" will prompt the user (typically) with a "Save as: foo.pdf" dialog, rather than opening it. This, however, needs to come from the request that is doing the download, so you can't do this during a redirect. However, ASP.NET offers Response.TransmitFile for this purpose. For example (assuming you aren't using MVC, which has other preferred options):

Response.Clear();
Response.ContentType = "application/pdf";
Response.AppendHeader("Content-Disposition", "attachment; filename=foo.pdf");
Response.TransmitFile(filePath);
Response.End();