Magnet Link Parameters Beyond the Torrent Hash

Magnet links are URI schemes used primarily in peer-to-peer (P2P) file-sharing networks to identify and locate files by their cryptographic content rather than their physical location. While the Exact Topic (xt) parameter containing the torrent info hash is the mandatory core of any BitTorrent magnet URI, several standard and extended parameters can be embedded alongside it. These parameters provide torrent clients with metadata such as file names, tracker addresses, fallback web seeds, specific file selections, and direct peer connections.

1. dn (Display Name)

The dn parameter specifies a human-readable file or folder name. It gives the BitTorrent client a provisional title to display in the user interface before the complete torrent metadata (the .torrent file payload) is fetched from peers. * Example: dn=Ubuntu-22.04-Desktop.iso

2. tr (Address Tracker)

The tr parameter defines tracker URLs used to discover active peers on the network. A magnet link can include multiple tr parameters to query several trackers simultaneously, improving connection reliability. * Example: tr=udp%3A%2F%2Ftracker.example.com%3A80%2Fannounce

3. ws (Web Seed)

The ws parameter specifies an HTTP or FTP address pointing directly to the file or payload root. BitTorrent clients supporting BEP 19 use this URL to download data directly from a standard web server when peer availability is low. * Example: ws=https%3A%2F%2Fmirror.example.com%2Ffiles%2Fdata.iso

4. xl (Exact Length)

The xl parameter specifies the total size of the targeted payload in bytes. It allows the client to immediately determine disk space requirements before obtaining full swarm metadata. * Example: xl=1073741824

5. xs (Exact Source)

The xs parameter provides a direct link to the source metadata, typically pointing to a downloadable .torrent file or a P2P content source. This allows the client to fetch metadata directly via HTTP/HTTPS instead of waiting to download it through the BitTorrent DHT network. * Example: xs=https%3A%2F%2Fexample.com%2Ftorrents%2Ffile.torrent

6. as (Acceptable Source)

The as parameter acts as a fallback direct download link to a web resource, referring to a general online resource rather than a dedicated BEP 19 web seed.

7. so (Select Only)

Defined in BEP 53, the so parameter specifies a comma-separated list of zero-indexed file indices to download from a multi-file torrent, allowing clients to ignore unwanted files automatically. * Example: so=0,2,4

8. x.pe (Peer Address)

The x.pe extension parameter directly provides the IP address and port of a known active peer, allowing instant peer connection without waiting for tracker responses or DHT lookups. * Example: x.pe=192.0.2.1:6881

9. kt (Keyword Topic)

The kt parameter contains a list of search keywords separated by plus (+) signs, utilized by search engines or P2P search mechanisms to categorize and discover the content. * Example: kt=linux+ubuntu+desktop+64bit

10. mt (Manifest Topic)

The mt parameter supplies a URI pointing to a manifest file containing a list of additional links, often used in broader content delivery formats.