Compress.cs

using System;
using System.IO.Compression;
using System.Web.Mvc;

namespace WellThen
{
    public class Compress : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {

            var encodingsAccepted = filterContext.HttpContext.Request.Headers["Accept-Encoding"];
            if (string.IsNullOrEmpty(encodingsAccepted)) return;

            encodingsAccepted = encodingsAccepted.ToLowerInvariant();
            var response = filterContext.HttpContext.Response;

            if (encodingsAccepted.Contains("deflate"))
            {
                response.AppendHeader("Content-encoding", "deflate");
                response.Filter = new DeflateStream(response.Filter, CompressionMode.Compress);
            }
            else if (encodingsAccepted.Contains("gzip"))
            {
                response.AppendHeader("Content-encoding", "gzip");
                response.Filter = new GZipStream(response.Filter, CompressionMode.Compress);
            }
        }
    }
}