Set Content-Type for testing from Firefox

Question

I need to do some REST service testing from Firefox where I set the Content-Type HTTP header to a specific value (to retrieve XML or JSON).

Is there a Firefox add-on that can do this?

Answer 1

There's Modify Headers "... You can modify the user-agent string, add headers to spoof a mobile request (e.g. x-up-calling-line-id) ..."

https://addons.mozilla.org/en-US/firefox/addon/967