torrent-file

Parse a torrent file and read encoded data.

Supports BitTorrent v1 (BEP-3), v2 (BEP-52), and hybrid torrent files.

This project is based on parse-torrent and node-bencode to parse the data of a torrent file. This library implements its own bencode encoder and decoder that does not use Buffer making it easier to use in browser or non node environments.

demo: https://torrent-file.pages.dev

Install

npm install @ctrl/torrent-file

API

info

The content of the metainfo file. Includes a version field ('v1', 'v2', or 'hybrid').

import fs from 'fs';

import { info } from '@ctrl/torrent-file';

const torrentInfo = info(fs.readFileSync('myfile'));
console.log({ torrentInfo });

files

Data about the files described in the torrent file, includes hashes of the pieces. For v2/hybrid torrents, files include piecesRoot and the result includes pieceLayers. pieces is undefined for v2-only torrents.

import fs from 'fs';

import { files } from '@ctrl/torrent-file';

const torrentFiles = files(fs.readFileSync('myfile'));
console.log({ torrentFiles });

hash

SHA-1 of torrent file info. This hash is commonly used by torrent clients as the ID of the torrent.

import fs from 'fs';

import { hash } from '@ctrl/torrent-file';

const torrentHash = hash(fs.readFileSync('myfile'));
console.log({ torrentHash });

hashes

Returns both v1 (SHA-1) and v2 (SHA-256) info hashes along with the detected torrent version. infoHashV2 is only present for v2 and hybrid torrents.

import fs from 'fs';

import { hashes } from '@ctrl/torrent-file';

const h = hashes(fs.readFileSync('myfile'));
console.log(h.version); // 'v1', 'v2', or 'hybrid'
console.log(h.infoHash); // SHA-1 (always present)
console.log(h.infoHashV2); // SHA-256 (v2/hybrid only)

Encode

Convert a parsed torrent object back into a .torrent file buffer.

import fs from 'fs';

import { toTorrentFile } from '@ctrl/torrent-file';

// Minimal example: create a .torrent buffer from fields
const buf = toTorrentFile({
  info: {
    // Required info fields
    'piece length': 16384,
    pieces: new Uint8Array(/* 20-byte SHA1 hashes concatenated */),
    name: 'example.txt',
    length: 12345,
  },
  // Optional fields
  announce: ['udp://tracker.publicbt.com:80/announce'],
  urlList: ['https://example.com/example.txt'],
  private: false,
  created: new Date(),
  createdBy: 'my-app/1.0.0',
  comment: 'Generated by @ctrl/torrent-file',
});

fs.writeFileSync('example.torrent', buf);

Demo

Run a local demo UI to drop a .torrent file and view parsed output:

pnpm install
pnpm demo:watch

To build the demo for static hosting:

pnpm demo:build

See Also

parse-torrent - torrent parsing based very heavily off this package
node-bencode - bencoder built into this project heavily based off this package