Transmission (BitTorrent client)

Transmission
Company type	Free software
Industry	Software
Founded	2005
Area served	Cross-platform
Products	BitTorrent client software
Website	transmissionbt.com

Adapted from the English Wikipedia article Transmission (BitTorrent client), available under CC BY-SA 4.0Updated 8 August 2025

Transmission is a BitTorrent client that offers several user interfaces, all built upon a cross-platform core. It is released as free software under the GNU General Public License, with certain components distributed under the MIT License.

Features

Transmission facilitates rapid downloading from numerous peers while also enabling file uploads. Users can add torrent files through the interface to manage download and upload queues, with options to customize settings for individual files. The software automatically seeds downloaded data, sharing it with others.

The application allows users to set priority levels for both torrents and individual files, affecting the sequence of downloads. It supports the Magnet URI scheme along with encrypted connections. Users can create torrents and utilize peer exchange compatible with clients like Vuze and μTorrent. A built-in web server provides remote management through a browser interface. Other capabilities include automatic port forwarding via UPnP and NAT-PMP, peer caching, blocklists to exclude undesirable peers, bandwidth throttling based on time (either globally or per torrent), partial support for IPv6, multiple trackers running simultaneously, Local Peer Discovery, use of the Micro Transport Protocol (μTP), and support for UDP trackers.

Although Transmission does not include a native RSS feed subscription feature for automated downloads, this functionality can be added through external extensions.

On macOS, Transmission offers specific features such as notifications through the Dock and Growl, automatic updates powered by Sparkle, and support for Universal Binary up to version 2.22.

The February 2023 release of Transmission 4.0.0 added compatibility with hybrid torrents that work with both v1 and hybrid (v1/v2) torrent formats.

Development

Support for Mac OS X v10.4 was discontinued starting with Transmission 1.60; version 1.54 remains the final release compatible with that system. While newer versions can be compiled from source via the project's website or package managers such as Fink or MacPorts, these builds are unofficial and issues specific to 10.4 are not resolved. Beginning with Transmission 2.30, only Apple Macs equipped with Intel processors are supported, marking the end of native compatibility with PowerPC hardware. Transmission 4.0 introduced support for Apple Silicon processors.

The core backend of Transmission (libTransmission) operates the Transmission daemon, which features a web-based front-end known as Clutch. Earlier iterations were adapted to serve as the update mechanism for Metal Gear Online on the PlayStation 3, and also functioned as the backend for the BitTorrent service provided by ImageShack.

Distribution and ports

A portable edition of Transmission is offered through PortableApps.com.

Ports

Transmission provides lightweight BitTorrent clients available in graphical user interface (GUI), command-line interface (CLI), and daemon formats. These clients offer a straightforward user experience built on a robust, cross-platform core.

Versions of the client are developed for multiple operating systems such as Unix-like, macOS, and BeOS/ZETA, each utilizing their respective native widget toolkits. For instance, transmission-gtk employs GTK, transmission-qt is based on Qt, and transmission-cli operates via a command-line interface. Additionally, transmission-remote-cli offers an ncurses-based interface designed for the daemon. The Python-transmissionrpc library implements Transmission’s JSON-RPC protocol.

There are unofficial adaptations as well, including a CLI client for iOS released in 2008 and iTransmission (2010), which is a GUI client for jailbroken iPhones supporting downloads over WiFi or 3G networks. For Android, the Transdroid application functions as a remote client but does not support direct downloading.

On Windows, Transmission-Qt can be compiled using MinGW, while the daemon and command-line utilities rely on Cygwin. Several third-party GUI tools exist, such as transmission-remote-dotnet and Transmission Remote GUI. Unofficial comprehensive builds of Transmission's Qt client and daemon are available; the daemon can operate as a Windows service with streaming capabilities for files being downloaded.

A cross-platform enhanced version with streaming functionality can be found on GitHub.

Transmission has also been ported to the Maemo operating system used on the Nokia N810 tablet and N900 smartphone, along with the MeeGo/Harmattan OS for the N9 and N950 devices, allowing direct torrent downloads on these platforms.

Website breach

In March 2016, a security incident involving Transmission’s official website was disclosed by Palo Alto Networks. Attackers managed to upload compromised .dmg files signed with an authentic Apple Developer certificate to circumvent macOS’s gatekeeper protection.

These infected installers contained ransomware—specifically a Mac-adapted version of Linux.Encoder.1, known as KeRanger—which encrypted users’ data and demanded payment of 1 Bitcoin (approximately US$404 at that time) in exchange for decryption keys. Transmission promptly urged Mac users to update to a secure release. In response, Apple revoked the compromised developer certificate and incorporated its signature into the system’s anti-malware tool, XProtect.

Reception

Transmission serves as the default BitTorrent client across numerous Unix and Linux distributions, including prominent distributions like Ubuntu, Mint, Fedora, Puppy, Zenwalk, and the GNOME edition of openSUSE.

Fon integrates Transmission into its routers by default, expanding its presence within network hardware markets.

Paul Huges from CNET commended Transmission for its "simplicity, lightweight nature, and comprehensive feature set." As of April 2017, it held the position of third most downloaded P2P application for Mac users on CNET.

External links