HomeController.cs

[HttpPost]
public bool SaveTemplate(DocumentViewModel model)
{
    string name = model.DocumentName;
    byte[] document = Convert.FromBase64String(model.BinaryDocument);

    using (TXTextControl.ServerTextControl tx =
        new TXTextControl.ServerTextControl())
    {
        tx.Create();
        tx.Load(document, TXTextControl.BinaryStreamType.InternalUnicodeFormat);

        tx.Save(Server.MapPath("/App_Data/documents/" + model.DocumentName),
            TXTextControl.StreamType.WordprocessingML);
    }

    return true;
}