rules.json

[
    {
      "id": 1,
      "priority": 1,
      "action": {
        "type": "modifyHeaders",
        "responseHeaders": [
          {
            "header": "Access-Control-Allow-Origin",
            "operation": "set",
            "value": "*"
          }
        ]
      },
      "condition": {
        "urlFilter": "*",
        "resourceTypes": ["xmlhttprequest"]
      }
    }
  ]