The config field must be pre-processed before it can be sent along with a request. It must be a base64 encoded JSON object.
An example within PHP:
<?php
$config = base64_encode(json_encode($config));
The rules##
The config is an array of tabs. It must have at least one tab.
This is an example of a valid config:
[{
"label": "Content",
"name": "tab1",
"hidden": false,
"elements": [{
"type": "text",
"name": "el1",
"required": false,
"label": "Blog post",
"value": "Hello world",
"microcopy": "",
"limit_type": "words",
"limit": 1000,
"plain_text": false
}]
}]