Creating ZIP and UNZIP files in ASP.NET using DotNetZip library.

DotNetZip is easy to use free class library for ziping and extracing the zip files.
Check this DotNetZip for more information.

Example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Ionic.Zlib;
using Ionic.Zip;
using System.IO;




namespace ZipFilesAspDotnet
{
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        #region Download ZIP File
        private void DownloadFile()
        {
            if (FileUpload1.HasFile)
            {
                //file upload folder App_Data
                string _fileName = FileuploadUtility.UploadFile(FileUpload1, Server.MapPath("~/App_Data/"), Session.SessionID);
                string[] _zip_fileName = _fileName.ToString().Split('.');
                Response.Clear();
                Response.ContentType = "application/zip";
                Response.AddHeader("content-disposition", "filename=" + "download_" + _zip_fileName.ToString() + ".zip");

                using (ZipFile zip = new ZipFile())
                {
                    zip.AddEntry(_fileName.ToString(), File.ReadAllBytes(Server.MapPath("~/App_Data/" + _fileName.ToString())));
                    zip.Save(Response.OutputStream);
                }
            }

        }
        #endregion

        #region EXTRACT THE ZIP FILE
        private void ExtractZipFile() 
        {
            string _fileName = FileuploadUtility.UploadFile(FileUpload1, Server.MapPath("~/App_Data/"), Session.SessionID);

            using (ZipFile zip1 = ZipFile.Read(Server.MapPath("~/App_Data/" + _fileName.ToString())))
            {
                
                foreach (ZipEntry e in zip1)
                {
                    //destination folder zipfiles
                    e.Extract(Server.MapPath("~/ZipFiles/"), ExtractExistingFileAction.OverwriteSilently);
                }
            }

        }
        #endregion

        protected void Button1_Click(object sender, EventArgs e)
        {
            DownloadFile();

        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            ExtractZipFile();
        }
    }
}

Download Sample