Today I needed to reformat a ginormous json file, but could not use the package-manager instructions for Emacs at github.com/joshwnj/json-modefor fire-wall/network issues.
So I manually installed all the needed files and put this in my .emacs file:
(require 'json-snatcher) ;from https://github.com/Sterlingg/json-snatcher
(require 'json-reformat) ;from https://github.com/gongo/json-reformat
(require 'json-mode) ;from https://github.com/joshwnj/json-mode;
Then to format a file, select all (c-x h) then m-x json-reformat-region. Works like a charm.
Thanks to the contributors for creating these packages!