0.3.17 | Bittornado
It uses a piece-sharing mechanism where multiple downloaders send pieces of files to each other simultaneously, reducing the bandwidth load on central servers.
Furthermore, BitTornado's engine was so robust that it was used as the underlying backend code for other massively popular clients of the era. Early versions of and the original Deluge client drew heavy inspiration from, or directly utilized, BitTornado's structural architecture. The Shift to Modern Clients bittornado 0.3.17