The purpose of this class is to generate a random short URL.

ShortUrlTokenGenerator.cs

using System;

public static class ShortUrlTokenGenerator
{
    private const string alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
    private static Random generator = new Random();

    public static string GenerateToken(int tokenLength)
    {
        var builder = new StringBuilder();

        for (var tokenIndex = 0; tokenIndex < tokenLength; tokenIndex++)
        {
            var randomCharacterIndex = generator.Next(alphabet.Length);
            builder.Append(alphabet[randomCharacterIndex]);
        }

        return builder.ToString();
    }
}