JSON is the “Javascript Object Notation”, basically a file format for data that’s suitable for easy processing by most modern web-based tools.
Several tilde.club programs expose APIs essentially by spitting out JSON as their output, including e.g. the list of recently updated home pages at
http://tilde.club/~delfuego/tilde.24h.json
If you’re looking to parse JSON from the command line with a minimum of code, the jq program may be your thing. jq is a filter that takes JSON on standard input and produces JSON on standard output. Along the way in the middle you can do various standard sorts of file munging on a field by field basis.