WebTorrent is a streaming torrent client for node.js and the browser. YEP, THAT'S RIGHT. THE BROWSER. It's written completely in JavaScript – the language of the web – so the same code works in both runtimes.

In node.js, this module is a simple torrent client, using TCP and UDP to talk to other torrent clients.

In the browser, WebTorrent uses WebRTC (data channels) for peer-to-peer transport. It can be used without browser plugins, extensions, or installations. It's Just JavaScript™. Note: WebTorrent does not support UDP/TCP peers in browser.

Simply include the webtorrent.min.js script on your page to start fetching files over WebRTC using the BitTorrent protocol, or require('webtorrent') with browserify. See demo apps and code examples below.

To make BitTorrent work over WebRTC (which is the only P2P transport that works on the web) we made some protocol changes. Therefore, a browser-based WebTorrent client or "web peer" can only connect to other clients that support WebTorrent/WebRTC.

To seed files to web peers, use a client that supports WebTorrent, e.g. webtorrent-hybrid or instant.io. We're also working on WebTorrent.app, a desktop client with a familiar UI that can connect to web peers. We hope established torrent clients (Transmission, Vuze, uTorrent, etc.) will add support for WebTorrent so they too can connect to both normal and web peers.

Warning: This is alpha software. Watch/star to follow along with progress.

• Torrent client for node.js & the browser (same npm module!)
• Insanely fast
• Download multiple torrents simultaneously, efficiently
• Pure Javascript (no native dependencies)
• Exposes files as streams
  • Fetches pieces from the network on-demand so seeking is supported (even before torrent is finished)
  • Seamlessly switches between sequential and rarest-first piece selection strategy
• Supports advanced torrent client features
  • magnet uri support via ut_metadata
  • peer discovery via dht, tracker, and ut_pex
  • protocol extension api for adding new extensions
• Comprehensive test suite (runs completely offline, so it's reliable and fast)

• WebRTC data channels for lightweight peer-to-peer communication with no plugins
• No silos. WebTorrent is a P2P network for the entire web. WebTorrent clients running on one domain can connect to clients on any other domain.
• Stream video torrents into a <video> tag (webm (vp8, vp9) or mp4 (h.264))
• Supports Chrome, Firefox, and Opera.

• Stream to AirPlay, Chromecast, VLC player, and many other devices/players

NOTE: To connect to "web peers" (browsers) in addition to normal BitTorrent peers, use webtorrent-hybrid which includes WebRTC support for node.

To install WebTorrent for use in node or the browser with require('webtorrent'), run:

npm install webtorrent

To install a webtorrent command line program, run:

npm install webtorrent -g

• Join us in Gitter or on freenode at #webtorrent to help with development or to hang out with some mad science hackers :)
• Create a new issue to report bugs
• Fix an issue. Note: WebTorrent is an OPEN Open Source Project!

• Instant.io – Streaming file transfer over WebTorrent (source code)
• Fastcast – Stream peer-to-peer audio and video content (source code)
• Webtorrentapp – A tool/platform for launching web apps from torrents
• People-driven web – Decentralized content management system (source code)
• PeerCloud - Serverless websites via WebTorrent
• βTorrent - Fully-featured WebTorrent browser client (source code)
• Niagara - Video player webtorrent with subtitles (zipped .srt(s))
• Seedshot - Ephemeral P2P screenshot sharing
• PeerWeb - Fetch and render a static website from a torrent
• Vique - Video player queue to share videos
• Your app here! (send a PR or open an issue with your app's URL)

WebTorrent is the first BitTorrent client that works in the browser, using open web standards (no plugins, just HTML5 and WebRTC)! It's easy to get started!

var WebTorrent = require('webtorrent')

var client = new WebTorrent()
var magnetURI = '...'

client.add(magnetURI, function (torrent) {
  // Got torrent metadata!
  console.log('Client is downloading:', torrent.infoHash)

  torrent.files.forEach(function (file) {
    // Display the file by appending it to the DOM. Supports video, audio, images, and
    // more. Specify a container element (CSS selector or reference to DOM node).
    file.appendTo('body')
  })
})

var dragDrop = require('drag-drop')
var WebTorrent = require('webtorrent')

var client = new WebTorrent()

// When user drops files on the browser, create a new torrent and start seeding it!
dragDrop('body', function (files) {
  client.seed(files, function (torrent) {
    console.log('Client is seeding:', torrent.infoHash)
  })
})

There are more examples in the examples folder.

WebTorrent works great with browserify, an npm module that let's you use node-style require() to organize your browser code and load modules installed by npm (as seen in the previous examples).

WebTorrent is also available as a standalone script (webtorrent.min.js) which exposes WebTorrent on the window object, so it can be used with just a script tag:

<script src="webtorrent.min.js"></script>

The WebTorrent script is also hosted on fast, reliable CDN infrastructure (Cloudflare and MaxCDN) for easy inclusion on your site:

<script src="https://cdn.jsdelivr.net/webtorrent/latest/webtorrent.min.js"></script>

WebTorrent also works in node.js, using the same npm module! It's mad science!

WebTorrent is available as a command line app. Here's how to use it:

$ npm install webtorrent -g
$ webtorrent --help

To download a torrent:

$ webtorrent magnet_uri

To stream a torrent to a device like AirPlay or Chromecast, just pass a flag:

$ webtorrent magnet_uri --airplay

There are many supported streaming options:

--airplay               Apple TV
--chromecast            Chromecast
--mplayer               MPlayer
--mpv                   MPV
--omx [jack]            omx [default: hdmi]
--vlc                   VLC
--xbmc                  XBMC
--stdout                standard out [implies --quiet]

In addition to magnet uris, webtorrent supports many ways to specify a torrent.

This API should work exactly the same in node and the browser. Open an issue if this is not the case.

Detect native WebRTC support in the environment.

if (WebTorrent.WEBRTC_SUPPORT) {
  // webrtc support!
} else {
  // fallback
}

Create a new WebTorrent instance.

If opts is specified, then the default options (shown below) will be overridden.

{
  dht: Boolean|Object,   // Enable DHT (default=true), or options object for DHT
  maxConns: Number,      // Max number of connections per torrent (default=55)
  nodeId: String|Buffer, // DHT protocol node ID (default=randomly generated)
  peerId: String|Buffer, // Wire protocol peer ID (default=randomly generated)
  rtcConfig: Object,     // RTCPeerConnection configuration object (default=STUN only)
  tracker: Boolean,      // Whether or not to enable trackers (default=true)
  wrtc: Object           // Custom webrtc implementation (in node, specify the [wrtc](https://www.npmjs.com/package/wrtc) package)
}

Start downloading a new torrent. Aliased as client.download.

torrentId can be one of:

• magnet uri (string)
• torrent file (buffer)
• info hash (hex string or buffer)
• parsed torrent (from parse-torrent)
• http/https url to a torrent file (string)
• filesystem path to a torrent file (string)

If opts is specified, then the default options (shown below) will be overridden.

{
  announce: [],   // Torrent trackers to use (added to list in .torrent or magnet uri)
  path: String,   // Folder to download files to (default=`/tmp/webtorrent/`)
  store: Function // Custom chunk store (must follow [abstract-chunk-store](https://www.npmjs.com/package/abstract-chunk-store) API)
}

If ontorrent is specified, then it will be called when this torrent is ready to be used (i.e. metadata is available). Note: this is distinct from the 'torrent' event which will fire for all torrents.

If you want access to the torrent object immediately in order to listen to events as the metadata is fetched from the network, then use the return value of client.add. If you just want the file data, then use ontorrent or the 'torrent' event.

Start seeding a new torrent.

input can be any of the following:

• path to the file or folder on filesystem (string) (Node.js only)
• W3C File object (from an <input> or drag and drop)
• W3C FileList object (basically an array of File objects)
• Node Buffer object (works in the browser)

Or, an array of string, File, or Buffer objects.

If opts is specified, it should contain the following types of options:

• options for create-torrent (to allow configuration of the .torrent file that is created)
• options for client.add (see above)

If onseed is specified, it will be called when the client has begun seeding the file.

Note: The torrent specification requires that every torrent have a name. If one is not explicitly provided through opts, WebTorrent will determine the torrent name with the following logic:

• If all of the files share a common prefix, that prefix will become the torrent name. For example, if all of the files start with /imgs/ the torrent name will be imgs
• Otherwise, the name of the first file passed in to client.seed, for example if the first file is /foo/bar/baz.txt, the torrent name will be baz.txt The torrent object will contain a list of files, whose names are prefixed with the torrent name. When creating a nameless torrent in Node, this will be intuitive. When doing the same in the browser, this may lead to confusing results.

Emitted when a torrent is ready to be used (i.e. metadata is available and store is ready). See the torrent section for more info on what methods a torrent has.

Remove a torrent from the client. Destroy all connections to peers and delete all saved file data. If callback is specified, it will be called when file data is removed.

Destroy the client, including all torrents and connections to peers. If callback is specified, it will be called when the client has gracefully closed.

An array of all torrents in the client.

Returns the torrent with the given torrentId. Convenience method. Easier than searching through the client.torrents array. Returns null if no matching torrent found.

Seed ratio for all torrents in the client.

Get the info hash of the torrent.

Get the magnet URI of the torrent.

An array of all files in the torrent. See the file section for more info on what methods the file has.

The attached bittorrent-swarm instance.

Get total bytes received from peers (including invalid data).

Get total bytes received from peers (excluding invalid data).

Get the time remaining in millis if downloading.

Get the total progress from 0 to 1.

Get the torrent ratio (seeded/downloaded).

Returns the download speed.

Returns the current upload speed.

Get the torrent download location.

Alias for client.remove(torrent).

Adds a peer to the underlying bittorrent-swarm instance.

Returns true if peer was added, false if peer was blocked by the loaded blocklist.

Selects a range of pieces to prioritize starting with start and ending with end (both inclusive) at the given priority. notify is an optional callback to be called when the selection is updated with new data.

Deprioritizes a range of previously selected pieces.

Marks a range of pieces as critical priority to be downloaded ASAP. From start to end (both inclusive).

Create an http server to serve the contents of this torrent, dynamically fetching the needed torrent pieces to satisfy http requests. Range requests are supported.

Returns an http.Server instance (got from calling http.createServer). If opts is specified, it is passed to the http.createServer function.

Visiting the root of the server / will show a list of links to individual files. Access individual files at /<index> where <index> is the index in the torrent.files array (e.g. /0, /1, etc.)

Here is a usage example:

var client = new WebTorrent()
var magnetURI = '...'

client.add(magnetURI, function (torrent) {
  // create HTTP server for this torrent
  var server = torrent.createServer()
  server.listen(port) // start the server listening to a port

  // visit http://localhost:<port>/ to see a list of files

  // access individual files at http://localhost:<port>/<index> where index is the index
  // in the torrent.files array

  // later, cleanup...
  server.close()
  client.destroy()
})

Temporarily stop connecting to new peers. Note that this does not pause new incoming connections, nor does it pause the streams of existing connections or their wires.

Resume connecting to new peers.

Emitted when all the torrent's files have been downloaded

Here is a usage example:

torrent.on('done', function(){
  console.log('torrent finished downloading');
  torrent.files.forEach(function(file){
     // do something with file
  })
})

Emitted every time a new chunk of data arrives, it's useful for reporting the current torrent status, for instance:

torrent.on('download', function(chunkSize){
  console.log('chunk size: ' + chunkSize);
  console.log('total downloaded: ' + torrent.downloaded);
  console.log('download speed: ' + torrent.downloadSpeed);
  console.log('progress: ' + torrent.progress);
  console.log('======');
})

Emitted whenever a new peer is connected for this torrent. wire is an instance of bittorrent-protocol, which is a node.js-style duplex stream to the remote peer. This event can be used to specify custom BitTorrent protocol extensions.

Here is a usage example:

var MyExtension = require('./my-extension')

torrent1.on('wire', function (wire, addr) {
  console.log('connected to peer with address ' + addr)
  wire.use(MyExtension)
})

See the bittorrent-protocol extension api docs for more information on how to define a protocol extension.

File name, as specified by the torrent. Example: 'some-filename.txt'

File path, as specified by the torrent. Example: 'some-folder/some-filename.txt'

File length (in bytes), as specified by the torrent. Example: 12345

Selects the file to be downloaded, but at a lower priority than files with streams. Useful if you know you need the file at a later stage.

Deselects the file, which means it won't be downloaded unless someone creates a stream for it.

Create a readable stream to the file. Pieces needed by the stream will be prioritized highly and fetched from the swarm first.

You can pass opts to stream only a slice of a file.

{
  start: startByte,
  end: endByte
}

Both start and end are inclusive.

Get the file contents as a Buffer.

The file will be fetched from the network with highest priority, and callback will be called once the file is ready. callback must be specified, and will be called with a an Error (or null) and the file contents as a Buffer.

file.getBuffer(function (err, buffer) {
  if (err) throw err
  console.log(buffer) // <Buffer 00 98 00 01 01 00 00 00 50 ae 07 04 01 00 00 00 0a 00 00 00 00 00 00 00 78 ae 07 04 01 00 00 00 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ...>
})

Show the file in a the browser by appending it to the DOM. This is a powerful function that handles many file types like video (.mp4, .webm, .m4v, etc.), audio (.m4a, .mp3, .wav, etc.), images (.jpg, .gif, .png, etc.), and other file formats (.pdf, .md, .txt, etc.).

The file will be fetched from the network with highest priority and streamed into the page (if it's video or audio). In some cases, video or audio files will not be streamable because they're not in a format that the browser can stream so the file will be fully downloaded before being played. For other non-streamable file types like images and PDFs, the file will be downloaded then displayed.

rootElem is a container element (CSS selector or reference to DOM node) that the content will be shown in. A new DOM node will be created for the content and appended to rootElem.

callback will be called once the file is visible to the user. callback must be specified, and will be called with a an Error (or null) and the new DOM node that is displaying the content.

file.appendTo('#containerElement', function (err, elem) {
  if (err) throw err // file failed to download or display in the DOM
  console.log('New DOM node with the content', elem)
})

Like file.appendTo but renders directly into given element (or CSS selector).

Get a url which can be used in the browser to refer to the file.

The file will be fetched from the network with highest priority, and callback will be called once the file is ready. callback must be specified, and will be called with a an Error (or null) and the Blob URL (String).

file.getBlobURL(function (err, url) {
  if (err) throw err
  var a = document.createElement('a')
  a.download = file.name
  a.href = url
  a.textContent = 'Download ' + file.name
  document.body.appendChild(a)
})

Most of the active development is happening inside of small npm modules which are used by WebTorrent.

"When applications are done well, they are just the really application-specific, brackish residue that can't be so easily abstracted away. All the nice, reusable components sublimate away onto github and npm where everybody can collaborate to advance the commons." — substack from "how I write modules"

These are the main modules that make up WebTorrent:

module	tests	version	description
webtorrent			torrent client (this module)
bittorrent-dht			distributed hash table client
bittorrent-peerid			identify client name/version
bittorrent-protocol			bittorrent protocol stream
bittorrent-swarm			bittorrent connection manager
bittorrent-tracker			bittorrent tracker server/client
create-torrent			create .torrent files
magnet-uri			parse magnet uris
parse-torrent			parse torrent identifiers
render-media			intelligently render media files
torrent-discovery			find peers via dht and tracker
ut_metadata			metadata for magnet uris (protocol extension)
ut_pex			peer discovery (protocol extension)

WebTorrent is an OPEN Open Source Project. Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit.

WebTorrent is only possible due to the excellent work of the following contributors:

In node, enable debug logs by setting the DEBUG environment variable to the name of the module you want to debug (e.g. bittorrent-protocol, or * to print all logs).

DEBUG=* webtorrent

Of course, this also works for the development version:

DEBUG=* ./bin/cmd.js

In the browser, enable debug logs by running this in the developer console:

localStorage.debug = '*'

Disable by running this:

localStorage.removeItem('debug')

• May 2015 (Data Terra Nemo) - WebTorrent: Mother of all demos
• Nov 2014 (JSConf Asia) - How WebTorrent Works
• Sep 2014 (NodeConf EU) – WebTorrent Mad Science (first working WebTorrent demo)
• May 2014 (JS.LA) – How I Built a BitTorrent Client in the Browser (progress update; node client working)
• Oct 2013 (RealtimeConf) – WebRTC Black Magic (first mention of idea for WebTorrent)

MIT. Copyright (c) Feross Aboukhadijeh.