Checks if an incoming string is HTML encoded

main.cs

using System;
using System.Web;

// add strings here to check if they are URL encoded
var incomingStrings = new[] { 
    "not encoded", 
    "encodéd",
    "dslkfjqmsdlkfjsdmfl",
    "AbIfZVn4y514sJbt%2BCCMJy6lsmsMi6uOWyhUhynDSf1MEqZ%2FWJnwUuCFO8zMFa4jCRWQrXHKdBaHd9CCdDNfoKDnPg1W9No16JQbL2DBEGg%3D"
};

foreach (var incomingString in incomingStrings)
{
    Console.WriteLine($"Is string '{incomingString}' URL encoded? {IsUrlEncoded(incomingString)}");
}

private bool IsUrlEncoded(string source)
{
    return source != HttpUtility.UrlDecode(source);
}

packages.config

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="ServiceStack.Text" version="4.0.62" targetFramework="net45" />
  <package id="ServiceStack.Client" version="4.0.62" targetFramework="net45" />
  <package id="ServiceStack.Interfaces" version="4.0.62" targetFramework="net45" />
</packages>