Hybrid torrent clients: bridge the classic swarm to browsers

Nuxtre's torrent client runs inside your browser. That is convenient — nothing to install — but it has a limit: a browser can only exchange pieces with other browsers and with web servers. Most of the BitTorrent network is out of its reach. A hybrid client on any computer bridges the gap. This guide explains why, and sets one up.

Two networks that don't talk

• Classic BitTorrent clients — qBittorrent, Tixati and most others — connect to each other directly over TCP, uTP and UDP, and find each other through trackers and the DHT.
• Browsers can't do that. Web pages may only open connections that browsers allow, and the one that suits file sharing is WebRTC. Torrents in a browser therefore use WebTorrent: the same pieces and the same info hashes, carried over WebRTC, with peers meeting on WebSocket trackers.

So a browser can download from other browsers, and from web seeds (ordinary web servers that hold the file). It can't reach a swarm made only of classic clients. On Nuxtre, torrents a browser can fetch are marked ▶ IN BROWSER; the rest come with a magnet link only.

What a hybrid client does

A hybrid client speaks both. It joins the classic swarm over TCP and UDP like any other client, and it also accepts browsers over WebRTC. Pieces it gets from one side, it can pass to the other.

One hybrid peer in a swarm is enough. While it is online and has pieces, every browser that looks for that torrent can fetch from it — yours included.

The client: WebTorrent Desktop

WebTorrent Desktop is a free, open-source hybrid client from the WebTorrent project, for Windows, macOS and Linux. In its makers' words, it "connects to both BitTorrent and WebTorrent peers". It is simple: add a magnet link, watch or listen while it downloads, keep it open to seed.

Its development has been slow, and the latest release is several years old; it still does the one thing this guide needs. Other clients are adding the same ability through the libtorrent library, whose newer versions support WebTorrent — check your client's release notes for "WebTorrent" or "WebRTC".

Set it up

1. Open the WebTorrent Desktop page here and press DOWNLOAD. Its official page opens in a new tab.
2. Install it for your system, then start it.
3. Find the torrent you want to bridge on Nuxtre's torrent index. On its page, use the 🧲 MAGNET LINK button; your browser offers to open it in WebTorrent Desktop.
4. WebTorrent Desktop adds the torrent and starts downloading from the classic swarm.
5. Leave it open. While it runs, it seeds to both networks.

Use it from the browser

1. On the same torrent's page on Nuxtre, open it in the Nuxtre client (the page offers TRY IN THE BROWSER when the index has not seen any browser peers yet).
2. Press Start in the client. It looks for peers on the WebSocket trackers, where WebTorrent Desktop announces too.
3. Within a minute or so the client should find your desktop client as a peer and start fetching. If the torrent is a film or music, it can play while it downloads.

Things to know

• Your IP address is visible to every peer you connect to, on both networks, as with any torrent client.
• Uploads use your connection. Set a limit if it slows other things down.
• Only bridge what you are allowed to share. A hybrid client shares on two networks at once; the rules are the same as for any torrent. The Torrents 101 guide covers them.
• Close it, and the bridge goes. Browsers can only fetch while a hybrid peer is online.

Later: Nuxtre's own program

Nuxtre plans a desktop program of its own that does all this in the background: a full torrent client on the classic network that is also a hybrid peer for browsers, tied to your Nuxtre account. Until it exists, WebTorrent Desktop is the simplest bridge.