JsonHelper.cs

using System;
using System.Linq;

namespace Vano.Tools.Azure
{
    public static class JsonHelper
    {
        private const string INDENT_STRING = "    ";
        public static string FormatJson(string json)
        {
            int indentation = 0;
            int quoteCount = 0;
            var result =
                from ch in json
                let quotes = ch == '"' ? quoteCount++ : quoteCount
                let lineBreak = ch == ',' && quotes % 2 == 0 ? ch + Environment.NewLine + String.Concat(Enumerable.Repeat(INDENT_STRING, indentation)) : null
                let openChar = ch == '{' || ch == '[' ? ch + Environment.NewLine + String.Concat(Enumerable.Repeat(INDENT_STRING, ++indentation)) : ch.ToString()
                let closeChar = ch == '}' || ch == ']' ? Environment.NewLine + String.Concat(Enumerable.Repeat(INDENT_STRING, --indentation)) + ch : ch.ToString()
                select lineBreak == null
                            ? openChar.Length > 1
                                ? openChar
                                : closeChar
                            : lineBreak;

            return String.Concat(result);
        }
    }
}