When demoing Hyperview to new engineers, there’s one comment that frequently comes up about the HXML data format: “XML, really? It’s bloated and outdated. Why not use JSON? It’s the future.” These comments imply that JSON is the “one true file format” that should be used for everything, but we don’t believe there’s such a thing. Each format makes tradeoffs in encoding, flexibility, and expressiveness to best suit a specific use case. The author makes a pretty solid argument that JSON is better for lists, while XML is better for trees.