What is a .torrent file?
BitTorrent Metadata File · Data · Bram Cohen / BitTorrent · 2001
A .torrent file is a small metadata file, not the content itself. It tells a BitTorrent client which files to download, their sizes and checksums, and where to find peers. You open it in a torrent client, which then fetches the actual data.
What is a .torrent file used for?
The .torrent holds only a description of a download: the list of files, a hash of each piece so the data can be verified, and tracker (announce) URLs that help find other people sharing it.
That is why a .torrent is tiny even when the download is huge, the real data lives on the peer-to-peer network, not in the file.
You open one in a BitTorrent client such as qBittorrent or Transmission, which reads the metadata and starts downloading. Magnet links do the same job without a separate file.
Using BitTorrent is perfectly legal; whether a particular download is depends entirely on the content and your rights to it.
What opens a .torrent file?
The .torrent format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- qBittorrent
- Transmission
macOS
- Transmission
- qBittorrent
Linux
- Transmission
- qBittorrent
Web
- Not applicable
Open a .torrent file step by step
- Confirm the file really is a .torrent. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with qBittorrent or Transmission.
- On Mac, use Transmission or qBittorrent.
- On Linux, try Transmission or qBittorrent.
- Still stuck? Convert the .torrent to Not convertible, which opens more widely.
Why can't I open my .torrent file?
Almost always because no installed app understands Torrent. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .torrent at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .torrent file
You can convert a .torrent file to Not convertible using a conversion tool or the export menu of an app that opens it.
What is the .torrent file signature (magic bytes)?
A .torrent file may start with the hex bytes 64 38 3A 61 6E 6E 6F 75 6E 63 65, which read as d8:announce in ASCII. Those bytes are a hint rather than a guarantee, so Torrent cannot be identified by its header alone.
These are the documented signatures for Torrent. For a full breakdown, see the BitTorrent file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 64 38 3A 61 6E 6E 6F 75 6E 63 65 | 0 | d8:announce | 'd8:announce' (bencoded dictionary; common but not guaranteed) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .torrent file?
A .torrent file is a small metadata file, not the content itself. It tells a BitTorrent client which files to download, their sizes and checksums, and where to find peers. You open it in a torrent client, which then fetches the actual data.
How do I open a .torrent file?
Open it in a BitTorrent client such as qBittorrent or Transmission. The client reads the file's metadata and downloads the actual content from other peers.
Is opening a .torrent file safe?
The .torrent itself is just a small text-like description and is safe to open in a client. The care is in what you then download: only fetch content you are allowed to, and scan the finished files.
Related formats
Sources
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