That's true but I think XML has the edge there. It has so many features like defining new types which you wouldn't normally see in JSON. One parser we used had

That's true but I think XML has the edge there. It has so many features like defining new types which you wouldn't normally see in JSON. One parser we used had a ten to one ratio - 50MB of XML meant 500MB of RAM usage when using a DOM parser. And that's taking into account the textual representation of XML is already >50% bloat with the closing tags etc.