manifest.json

{
    "manifest": "1",
    "client_id": "1632851369",
    "version": "1.0.0",
    "locale": {
        "default": "en-us",
        "supported": ["en-us"]
    },
    "elements": [
        {
            "path": "files",
            "name": "Subscription Widget",
            "version": "1.0.0",
            "settings": {
                "config": {
                    "external": {
                        "url": "http://app.mailjet.com/widget?force_iframe=1&p=weebly",
                        "label": "Copy and Paste your Mailjet Widget Code"
                    },
                    "autopop": false
                },
                "properties": [
                    {
                        "type": "group",
                        "name": "settings",
                        "label": "Settings",
                        "properties": [
                            {
                                "name": "widgetcode",
                                "default": "",
                                "type": "text",
                                "label": "Mailjet Widget"
                            }]
                    }]
            }
        }]
}