Every object has to be named inside the parent object:

{ "data": {
    "stuff": {
        "onetype": [
            { "id": 1, "name": "" },
            { "id": 2, "name": "" }
        ],
        "othertype": [
            { "id": 2, "xyz": [-2, 0, 2], "n": "Crab Nebula", "t": 0, "c": 0, "d": 5 }
        ]
    },
    "otherstuff": {
        "thing":
            [[1, 42], [2, 2]]
    }
  }
}

So you cant declare an object like this:

var obj = {property1, property2};

It has to be

var obj = {property1: 'value', property2: 'value'};

Many JSON parsers and formatters use recursion (i.e., ArduinoJSON and the IBM DastaPower Gateway).

This means that deeply nested JSON objects can be used to attack implementations that use this approach (i.e. see this older jansson issue)).

Originally, the JSON testing suite offered by json.org was testing to make sure parsers would fail at 22 levels of nesting.

This also makes sense where data accessing is concerned. Accessing nested data is less readable (and less maintainable) than multiple storage objects.

So, although there's no official limits to JSON nesting levels, in order to allow your data to be portable and safe, I would not recommend any nesting level above 16.

IMHO, the 16-31 nesting levels should be considered a hazard zone and anything above 32 nesting levels should be considered as a design error.