Pretty JSON encoding for Active Support

active_support_pretty_json_encoding.rb

require 'active_support/json/encoding'

module ActiveSupport
  module JSON
    module Encoding
      class JSONGemEncoder
        # Replaces the JSON gem encoder's string-ify method with a
        # pretty-generator implementation. Just clobbers the original method,
        # so makes assumptions about method name, arguments and
        # implementation details. That makes it Rails version dependent.
        # Useful just for development only.
        def stringify jsonified
          ::JSON.pretty_generate jsonified, quirks_mode: true, max_nesting: false
        end
      end
    end
  end
end if Rails.env.development? && Gem::Dependency.new('rails', '~> 5.0.2').match?('rails', Rails.version)

For Rails applications, put this in config/initializers.

You are a life savior! FYI, it still works fine in Rails 6.1.4.4.

Cheers ZzZombo, glad to know it still works.