Vim Pretty JSON

:%!python -m json.tool

Or add to .vimrc 

au FileType json setlocal equalprg=python\ -m\ json.tool

Refer

  1. https://pascalprecht.github.io/2014/07/10/pretty-print-json-in-vim/
  2. https://coderwall.com/p/tpfysw/pretty-format-json-in-vim