Creating and Seeding Torrents

WebTorrent makes it easy to create new torrents and seed them to the network. You can seed files from the browser or Node.js, and share content with anyone using BitTorrent.

Seeding from Node.js

Create a client

import WebTorrent from 'webtorrent'

const client = new WebTorrent()

Seed a file or folder

client.seed('/path/to/file.mp4', torrent => {
  console.log('Seeding:', torrent.name)
  console.log('Magnet URI:', torrent.magnetURI)
  console.log('Info hash:', torrent.infoHash)
})

Share the magnet URI

The magnet URI can be shared with others to download your torrent:

console.log('Share this link:', torrent.magnetURI)

Seeding a Single File

import WebTorrent from 'webtorrent'

const client = new WebTorrent()

client.seed('/path/to/video.mp4', torrent => {
  console.log('Client is seeding:', torrent.name)
  console.log('Magnet URI:', torrent.magnetURI)
  
  // Keep seeding indefinitely
  console.log('Seeding... Press Ctrl+C to stop')
})

Seeding a Folder

client.seed('/path/to/folder', torrent => {
  console.log('Seeding folder:', torrent.name)
  console.log('Files:', torrent.files.length)
  
  torrent.files.forEach(file => {
    console.log('  -', file.path, `(${file.length} bytes)`)
  })
})

Seeding Multiple Files

import WebTorrent from 'webtorrent'

const client = new WebTorrent()

const files = [
  '/path/to/file1.mp4',
  '/path/to/file2.mp4',
  '/path/to/file3.mp4'
]

client.seed(files, torrent => {
  console.log('Seeding', torrent.files.length, 'files')
  console.log('Magnet URI:', torrent.magnetURI)
})

Seeding from the Browser

In the browser, you can seed files selected by the user:

Create a file input

<input type="file" id="fileInput" multiple>
<div id="status"></div>

Handle file selection

import WebTorrent from 'webtorrent'

const client = new WebTorrent()
const fileInput = document.querySelector('#fileInput')
const status = document.querySelector('#status')

fileInput.addEventListener('change', event => {
  const files = event.target.files
  
  client.seed(files, torrent => {
    status.innerHTML = `
      Seeding: ${torrent.name}<br>
      Magnet URI: <input value="${torrent.magnetURI}" readonly>
    `
  })
})

Drag and Drop Seeding

Use the drag-drop package for better UX:

import dragDrop from 'drag-drop'
import WebTorrent from 'webtorrent'

const client = new WebTorrent()

// When user drops files on the browser
dragDrop('body', files => {
  client.seed(files, torrent => {
    console.log('Client is seeding:', torrent.infoHash)
    
    // Display magnet URI
    const magnetLink = document.createElement('a')
    magnetLink.href = torrent.magnetURI
    magnetLink.textContent = 'Magnet Link'
    document.body.appendChild(magnetLink)
    
    // Display download link for .torrent file
    const torrentLink = document.createElement('a')
    torrentLink.href = URL.createObjectURL(torrent.torrentFileBlob)
    torrentLink.download = torrent.name + '.torrent'
    torrentLink.textContent = 'Download .torrent'
    document.body.appendChild(torrentLink)
  })
})

Complete Browser Example

<!DOCTYPE html>
<html>
<head>
  <title>WebTorrent Seeder</title>
  <style>
    body { 
      font-family: Arial, sans-serif; 
      padding: 20px;
    }
    #dropZone {
      border: 3px dashed #ccc;
      border-radius: 10px;
      padding: 40px;
      text-align: center;
      margin: 20px 0;
      cursor: pointer;
    }
    #dropZone.dragover {
      background: #f0f0f0;
      border-color: #666;
    }
    .torrent {
      margin: 20px 0;
      padding: 15px;
      border: 1px solid #ddd;
      border-radius: 5px;
    }
  </style>
</head>
<body>
  <h1>Seed Files with WebTorrent</h1>
  <div id="dropZone">Drop files here or click to select</div>
  <input type="file" id="fileInput" multiple style="display: none">
  <div id="torrents"></div>

  <script type="module">
    import WebTorrent from 'https://esm.sh/webtorrent/dist/webtorrent.min.js'

    const client = new WebTorrent()
    const dropZone = document.querySelector('#dropZone')
    const fileInput = document.querySelector('#fileInput')
    const torrentsDiv = document.querySelector('#torrents')

    // Handle file selection
    function seedFiles(files) {
      client.seed(files, torrent => {
        const div = document.createElement('div')
        div.className = 'torrent'
        div.innerHTML = `
          <h3>${torrent.name}</h3>
          <p><strong>Files:</strong> ${torrent.files.length}</p>
          <p><strong>Size:</strong> ${(torrent.length / 1024 / 1024).toFixed(2)} MB</p>
          <p><strong>Info Hash:</strong> ${torrent.infoHash}</p>
          <p><strong>Magnet URI:</strong><br>
            <input type="text" value="${torrent.magnetURI}" readonly 
                   style="width: 100%; font-size: 11px">
          </p>
          <p><strong>Upload:</strong> <span class="upload">0</span> KB/s</p>
          <p><strong>Peers:</strong> <span class="peers">0</span></p>
        `
        torrentsDiv.appendChild(div)

        // Update stats
        const uploadSpan = div.querySelector('.upload')
        const peersSpan = div.querySelector('.peers')
        setInterval(() => {
          uploadSpan.textContent = (torrent.uploadSpeed / 1024).toFixed(1)
          peersSpan.textContent = torrent.numPeers
        }, 1000)
      })
    }

    // Click to select files
    dropZone.addEventListener('click', () => fileInput.click())
    fileInput.addEventListener('change', e => seedFiles(e.target.files))

    // Drag and drop
    dropZone.addEventListener('dragover', e => {
      e.preventDefault()
      dropZone.classList.add('dragover')
    })

    dropZone.addEventListener('dragleave', () => {
      dropZone.classList.remove('dragover')
    })

    dropZone.addEventListener('drop', e => {
      e.preventDefault()
      dropZone.classList.remove('dragover')
      seedFiles(e.dataTransfer.files)
    })
  </script>
</body>
</html>

Seeding Options

Customize torrent creation with various options:

client.seed(files, {
  // Torrent metadata
  name: 'My Custom Torrent Name',
  comment: 'Created with WebTorrent',
  createdBy: 'WebTorrent/1.0',
  creationDate: new Date(),
  
  // Privacy settings
  private: false,              // If true, disable DHT and PEX
  
  // Trackers
  announceList: [
    ['udp://tracker.opentrackr.org:1337'],
    ['wss://tracker.btorrent.xyz']
  ],
  
  // Web seeds (HTTP/HTTPS sources)
  urlList: [
    'https://example.com/files/'
  ],
  
  // Piece length (16 KB to 16 MB, default: automatic)
  pieceLength: 1024 * 1024,    // 1 MB pieces
  
  // Storage options
  path: '/downloads',           // Download location (Node.js only)
  skipVerify: true             // Skip hash verification (when seeding)
}, torrent => {
  console.log('Torrent created:', torrent.name)
})

Recommended Trackers

const trackers = [
  // WebSocket trackers (browser-compatible)
  'wss://tracker.btorrent.xyz',
  'wss://tracker.openwebtorrent.com',
  'wss://tracker.fastcast.nz',
  
  // UDP trackers (Node.js only)
  'udp://tracker.opentrackr.org:1337',
  'udp://tracker.openbittorrent.com:6969',
  'udp://explodie.org:6969'
]

client.seed(files, {
  announceList: trackers.map(t => [t])
}, torrent => {
  console.log('Announced to trackers')
})

Browser peers can only use WebSocket (wss://) trackers. UDP trackers only work in Node.js.

Getting the .torrent File

You can save the generated .torrent file:

In Node.js

import fs from 'fs'

client.seed('/path/to/file.mp4', torrent => {
  // Get .torrent file as Buffer
  const torrentFile = torrent.torrentFile
  
  // Save to disk
  fs.writeFileSync(`${torrent.name}.torrent`, torrentFile)
  console.log('Saved torrent file:', `${torrent.name}.torrent`)
})

In Browser

client.seed(files, torrent => {
  // Get .torrent file as Blob
  const blob = torrent.torrentFileBlob
  
  // Create download link
  const url = URL.createObjectURL(blob)
  const a = document.createElement('a')
  a.href = url
  a.download = torrent.name + '.torrent'
  a.textContent = 'Download .torrent file'
  document.body.appendChild(a)
})

Monitoring Seeding Progress

Track upload statistics and peer connections:

client.seed(files, torrent => {
  console.log('Seeding started:', torrent.name)
  
  // Log stats every 5 seconds
  setInterval(() => {
    console.log('\nSeeding Stats:')
    console.log('  Uploaded:', (torrent.uploaded / 1024 / 1024).toFixed(2), 'MB')
    console.log('  Upload speed:', (torrent.uploadSpeed / 1024).toFixed(1), 'KB/s')
    console.log('  Peers:', torrent.numPeers)
    console.log('  Ratio:', torrent.ratio.toFixed(2))
  }, 5000)
  
  // Monitor uploads
  torrent.on('upload', bytes => {
    console.log('Uploaded', bytes, 'bytes')
  })
  
  // Monitor peer connections
  torrent.on('wire', (wire, addr) => {
    console.log('Connected to peer:', addr)
  })
})

Hybrid Seeding (Browser + Node.js)

To seed to both browser peers (WebRTC) and traditional BitTorrent clients (TCP/UDP), use webtorrent-hybrid in Node.js:

npm install webtorrent-hybrid

import WebTorrent from 'webtorrent-hybrid'

const client = new WebTorrent()

client.seed('/path/to/file.mp4', torrent => {
  console.log('Seeding to both web peers and traditional peers')
  console.log('Magnet URI:', torrent.magnetURI)
  
  torrent.on('wire', (wire, addr) => {
    console.log('Peer type:', wire.type)  // 'webrtc', 'tcpOutgoing', etc.
  })
})

Use webtorrent-hybrid to make your Node.js seeds accessible to browser-based WebTorrent clients.

Seeding from Existing Torrents

You can seed existing torrents you’ve already downloaded:

import fs from 'fs'
import WebTorrent from 'webtorrent'

const client = new WebTorrent()

// Load existing .torrent file
const torrentFile = fs.readFileSync('./existing.torrent')

// Add with preloaded store
client.add(torrentFile, {
  path: '/path/to/existing/files',  // Where files already exist
  skipVerify: false                  // Verify hashes
}, torrent => {
  console.log('Verifying existing files...')
  
  torrent.on('ready', () => {
    console.log('Now seeding:', torrent.name)
  })
})

Advanced: Custom Piece Length

Choose piece length based on total size:

import WebTorrent from 'webtorrent'

function getOptimalPieceLength(totalSize) {
  // Aim for around 1000-2000 pieces
  const targetPieces = 1500
  const size = totalSize / targetPieces
  
  // Round to power of 2 between 16 KB and 16 MB
  const minSize = 16 * 1024        // 16 KB
  const maxSize = 16 * 1024 * 1024 // 16 MB
  
  let pieceLength = minSize
  while (pieceLength < size && pieceLength < maxSize) {
    pieceLength *= 2
  }
  
  return pieceLength
}

const files = ['/path/to/large/file.mp4']
const totalSize = 5 * 1024 * 1024 * 1024 // 5 GB

client.seed(files, {
  pieceLength: getOptimalPieceLength(totalSize)
}, torrent => {
  console.log('Piece length:', torrent.pieceLength, 'bytes')
  console.log('Total pieces:', torrent.pieces.length)
})

Smaller pieces = more overhead but better for slow connections. Larger pieces = less overhead but worse for seeking in video files. The default automatic selection usually works well.

Graceful Shutdown

Properly close the client when done seeding:

const client = new WebTorrent()

client.seed(files, torrent => {
  console.log('Seeding... Press Ctrl+C to stop')
})

// Handle shutdown
process.on('SIGINT', () => {
  console.log('\nStopping...')
  client.destroy(err => {
    if (err) console.error('Error:', err)
    else console.log('Client destroyed')
    process.exit(0)
  })
})

Complete Seeding Example

Full Node.js example with all features:

import WebTorrent from 'webtorrent-hybrid'
import fs from 'fs'

const client = new WebTorrent()

// Files to seed
const files = process.argv.slice(2)

if (files.length === 0) {
  console.error('Usage: node seed.js <file1> [file2] ...')
  process.exit(1)
}

console.log('Creating torrent...\n')

client.seed(files, {
  name: 'My Shared Files',
  comment: 'Shared with WebTorrent',
  announceList: [
    ['wss://tracker.btorrent.xyz'],
    ['wss://tracker.openwebtorrent.com'],
    ['udp://tracker.opentrackr.org:1337']
  ]
}, torrent => {
  console.log('✓ Torrent created!')
  console.log('Name:', torrent.name)
  console.log('Files:', torrent.files.length)
  console.log('Size:', (torrent.length / 1024 / 1024).toFixed(2), 'MB')
  console.log('Info Hash:', torrent.infoHash)
  console.log('\nMagnet URI:')
  console.log(torrent.magnetURI)
  
  // Save .torrent file
  const torrentPath = `./${torrent.name}.torrent`
  fs.writeFileSync(torrentPath, torrent.torrentFile)
  console.log('\n✓ Saved .torrent file:', torrentPath)
  
  console.log('\nSeeding... Press Ctrl+C to stop\n')
  
  // Stats
  setInterval(() => {
    console.log('Uploaded:', (torrent.uploaded / 1024 / 1024).toFixed(2), 'MB')
    console.log('Speed:', (torrent.uploadSpeed / 1024).toFixed(1), 'KB/s')
    console.log('Peers:', torrent.numPeers)
    console.log('Ratio:', torrent.ratio.toFixed(2))
    console.log('---')
  }, 5000)
})

// Graceful shutdown
process.on('SIGINT', () => {
  console.log('\n\nShutting down...')
  client.destroy(() => {
    console.log('Done.')
    process.exit(0)
  })
})

​Seeding from Node.js

​Seeding a Single File

​Seeding a Folder

​Seeding Multiple Files

​Seeding from the Browser

​Drag and Drop Seeding

​Complete Browser Example

​Seeding Options

​Recommended Trackers

​Getting the .torrent File

​In Node.js

​In Browser

​Monitoring Seeding Progress

​Hybrid Seeding (Browser + Node.js)

​Seeding from Existing Torrents

​Advanced: Custom Piece Length

​Graceful Shutdown

​Complete Seeding Example

Seeding from Node.js

Seeding a Single File

Seeding a Folder

Seeding Multiple Files

Seeding from the Browser

Drag and Drop Seeding

Complete Browser Example

Seeding Options

Recommended Trackers

Getting the .torrent File

In Node.js

In Browser

Monitoring Seeding Progress

Hybrid Seeding (Browser + Node.js)

Seeding from Existing Torrents

Advanced: Custom Piece Length

Graceful Shutdown

Complete Seeding Example