torrent-stream
The low level streaming torrent engine that peerflix uses
...This enables developers to build custom torrent-based applications — not just streaming video, but also file downloaders, partial-download managers, or peer-to-peer file distribution tools. The library supports selecting which files to download (useful in multi-file torrents), serves requested pieces on demand, and allows streaming large files without fully writing them to disk upfront — ideal for memory-efficient or on-the-fly consumption contexts. Because torrent-stream is a plain Node.js module, you can embed it in any JavaScript-based backend or tool, integrate it with HTTP servers to serve torrent content, or combine it with other processing pipelines.