modal_with_blocks.json

{
    "type": "modal",
    "blocks": [
        {
            "type": "section",
            "block_id": "1",
            "text": {
                "type": "mrkdwn",
                "text": "first section block"
            }
        },
        {
            "type": "divider",
            "block_id": "2"
        },
        {
            "type": "section",
            "block_id": "3",
            "text": {
                "type": "mrkdwn",
                "text": "second section block"
            }
        }
    ],
    "title": {
        "type": "plain_text",
        "text": "Hello, world!"
    },
    "close": {
        "type": "plain_text",
        "text": "Close button"
    },
    "submit": {
        "type": "plain_text",
        "text": "Submit button"
    }
}