Where can I download a simple Windows GUI app that can consume an HTTP POST, display its contents, and return 200?
This is really best done by writing a script and loading it into your favourite web server (IIS, Apache, whatever), and then pushing the POST to this file.
<pre><?php print_r($_POST) ?></pre>
<% For Each Item In Request.Form For x=1 To Request.Form(item).Count Response.Write Item & ": " & Request.Form(Item)(x) & "<br>" Next Next %>
Credit where credit's due, ASP code blatantly lifted from here
200 response is automatically generated by the web server, since we are outputting valid code.
If you need a more of a "catch all" response (i.e. you want the web server to run this script regardless of whatever URL you're POSTing to) this can be done with a rewrite rule.
If you have/are willing to install Python, you can do it easily with
dumdum, a tool I wrote
No code required.