First off, please only post your topic in one place. It avoids confusion if there's not duplicate topics in multiple locations.
I use a plugin called SmartPill to run any native PHP from within filemaker. It's a very powerful thing especially if you come from a PHP background like I did.
SmartPill supports all PHP data arrays as far as I know. Micah Woods can answer any questions you have about the plugin, and has usually been responsive to any of my questions.
Well, if you use our MBS Filemaker Plugin, you can use our JSON functions to build the JSON string and also use the CURL functions to do the POST operation.
Examples are included with plugins.
When doing the CURL.perform, is there a way to see the raw data that is being sent? the server I'm talking to wants it in a particular format, and I'm getting a parse error from it.