data.rb

#!/usr/bin/env ruby

require "json"

DATA.each do |file|
  json = JSON.parse(File.read(file))
  File.open(file,"w") do |out|
    out.puts JSON.pretty_generate(json)
  end
end

__END__
tmp/blah.json
tmp/foo.json
test/test.json
test/test2.json