Download all Files from SharePoint Document Library

Using Power shell command use below code :

######################## Start Variables ########################
######################## Varun's Script######################
$destination = "C:\\tools\\Folder"
$webUrl = "<Url of the specific site>"
$listUrl = "<Url of the specific list. This url is complete Url and NOT relative url>"
##############################################################
$web = Get - SPWeb - Identity $webUrl
$list = $web.GetList($listUrl)

function ProcessFolder {
    param($folderUrl)
    $folder = $web.GetFolder($folderUrl)
    foreach($file in $folder.Files) {#
        Ensure destination directory
        $destinationfolder = $destination + "/" + $folder.Url
        if (!(Test - Path - path $destinationfolder)) {
            $dest = New - Item $destinationfolder - type directory
        }#
        Download file
        $binary = $file.OpenBinary()
        $stream = New - Object System.IO.FileStream($destinationfolder + "/" + $file.Name), Create
        $writer = New - Object System.IO.BinaryWriter($stream)
        $writer.write($binary)
        $writer.Close()
    }
}#
Download root files
ProcessFolder($list.RootFolder.Url)# Download files in folders
foreach($folder in $list.Folders) {
    ProcessFolder($folder.Url)
}

Using Server object model use below code:

static void Main(string[] args) {
    using(SPSite site = new SPSite("http://site name")) {
        using(SPWeb web = site.OpenWeb()) {
            // Library name - Shared Documents
            SPList list = web.Lists["Shared Documents"];
            processFolder(list.RootFolder.Url);
            foreach(SPFolder folder in list.RootFolder.SubFolders) {
                processFolder(folder.Url);
            }
        }
    }
}
public static void processFolder(string folderURL) {
    string Destination = @
    "c:\\temp";
    using(SPSite site = new SPSite("http://yoursite")) {
        using(SPWeb web = site.OpenWeb()) {
            SPFolder folder = web.GetFolder(folderURL);
            foreach(SPFile file in folder.Files) {
                string destinationfolder = Destination + "/" + folder.Url;
                byte[] binary = file.OpenBinary();
                if (!Directory.Exists(destinationfolder)) {
                    Directory.CreateDirectory(destinationfolder);
                }
                FileStream stream = new FileStream(destinationfolder + "/" + file.Name, FileMode.Create);
                BinaryWriter writer = new BinaryWriter(stream);
                writer.Write(binary);
                writer.Close();
            }
        }
    }
}

Using Client object model use below code:

static void Main(string[] args) {
    var site = new ClientContext("http://sitename/");
    var web = site.Web;
    site.Load(web);
    site.ExecuteQuery();
    // Library name - Shared Documents
    List list = web.Lists.GetByTitle("Shared Documents");
    site.Load(list);
    site.ExecuteQuery();
    site.Load(list.RootFolder);
    site.ExecuteQuery();
    site.Load(list.RootFolder.Folders);
    site.ExecuteQuery();
    processFolderClientobj(list.RootFolder.ServerRelativeUrl);
    foreach(Folder folder in list.RootFolder.Folders) {
        processFolderClientobj(folder.ServerRelativeUrl);
    }
}

public static void processFolderClientobj(string folderURL) {
    string Destination = @
    "c:\\temp";
    var site = new ClientContext("http://sitename/");
    var web = site.Web;
    site.Load(web);
    site.ExecuteQuery();
    Folder folder = web.GetFolderByServerRelativeUrl(folderURL);
    site.Load(folder);
    site.ExecuteQuery();
    site.Load(folder.Files);
    site.ExecuteQuery();
    foreach(Microsoft.SharePoint.Client.File file in folder.Files) {
        string destinationfolder = Destination + "/" + folder.ServerRelativeUrl;
        Stream fs = Microsoft.SharePoint.Client.File.OpenBinaryDirect(site, file.ServerRelativeUrl).Stream;
        byte[] binary = ReadFully(fs);
        if (!Directory.Exists(destinationfolder)) {
            Directory.CreateDirectory(destinationfolder);
        }
        FileStream stream = new FileStream(destinationfolder + "/" + file.Name, FileMode.Create);
        BinaryWriter writer = new BinaryWriter(stream);
        writer.Write(binary);
        writer.Close();
    }
}
public static byte[] ReadFully(Stream input) {
    byte[] buffer = new byte[16 * 1024];
    using(MemoryStream ms = new MemoryStream()) {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0) {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}