UploadFile WebAPI - Client

BlobHelper.cs

using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace UploadImageTest
{
    public class BlobHelper
    {
        public static async Task<IList<string>> UploadPhoto(params FileUploadCommand[] fileCommands)
        {
            try
            {
                var content = new MultipartFormDataContent();

                foreach (var fileCommand in fileCommands)
                {
                    var fileContent = new ByteArrayContent(fileCommand.Bytes);
                    fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                    {
                        FileName = Guid.NewGuid().ToString() + fileCommand.Extension
                    };

                    content.Add(fileContent);
                }

                using (var client = new HttpClient())
                {
                    var response = await client.PostAsync("http://localhost:50461/core/api/Test/UploadFile", content);

                    response.EnsureSuccessStatusCode();

                    return await response.Content.ReadAsAsync<IList<string>>(); //retorna list de urls do blob
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
    }

    public class FileUploadCommand
    {
        public static FileUploadCommand CreateFromFile(string file)
        {
            var f = new FileUploadCommand()
            {
                Bytes = File.ReadAllBytes(file),
                Extension = Path.GetExtension(file)
            };

            return f;
        }

        public byte[] Bytes { get; set; }
        public string Extension { get; set; }
    }
}

UploadImage.TestProgram.cs

using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace UploadImageTest
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            BlobHelper.UploadPhoto(
                FileUploadCommand.CreateFromFile(@"C:\Users\Angus\Desktop\t.png")
                //,FileUploadCommand.CreateFromFile(@"C:\Users\Angus\Desktop\appprodutor.png")
                )
                .Wait();
        }
    }

    
}

Instalar
Microsoft.AspNet.WebApi.Client