I think the reason JSON doesn't take well to strong typing is that it is designed for Javascript. When you pass some Javascript object to the JSON encoder how is it supposed to decide which numeric representation to use? Does it always go for the smallest one that works? The Javascript decoder at the other end is just going to throw away that type information anyway, so all it is good for is verifying the data while you are parsing it. Maybe not a totally useless thing to do but it's a lot of work to get that modest benefit.