Erm, maybe file based? JSON is the king if you count exchanges worldwide a sec. Maybe no 2 is form-data which is basically email multipart, and if course there's email as a format. Very common =)

I meant file-based.

JSON: because XML is too hard.

Developers: hey, let's hack everything XML had back onto JSON except worse and non-standardized. Because it turns out you need those things sometimes!

JSON isn't great for tabular data. And an awful lot of data is tabular.

Yeah, I don’t like parsing XML, but I’d rather do that than deal with the Lovecraftian API design that comes with complex JSON representations.

JSON tabular data only adds a couple of brackets per line and at the start/end of the file vs CSV. In exchange for these bits (that basically disappear when compressed), you get a guaranteed standard formatting. Seems like a decent tradeoff to me.