.NET (Core and Framework)

Stream rs = req.GetResponse().GetResponseStream();
      // Send file to client.
      while (fileLength > 0)
      {
          if (Response.IsClientConnected)
          {
              int length = rs.Read(buffer, 0, 10240);

              Response.OutputStream.Write(buffer, 0, length);

               Thread.Sleep(20);

              Response.Flush();

              fileLength = fileLength - length;
          }
          else
          {
              fileLength = -1;
          }
      }