3.3.1 (Build 29963) (July 19, 2013) [±]
OS X for Intel
1.8.4 (Build 29561) (April 3, 2013) [±]
1.16 (Beta) (June 19, 2013) [±]
3.0 (Server alpha; build 27079) (May 29, 2012) [±]
3.3.2 (Beta; build 29944) (July 15, 2013) [±]
3.4 (Alpha; build 29972) (July 23, 2013) [±]
µTorrent (or uTorrent; commonly abbreviated as "µT" or "uT") is a free-of-charge, ad-supported, closed source BitTorrent client owned by BitTorrent, Inc. It is the most widely used BitTorrent client outside China (where Xunlei is more popular.) The "µ"(Greek letter "mu") in its name comes from the SI prefix "micro-", referring to the program's small memory footprint: the program was designed to use minimal computer resources while offering functionality comparable to larger BitTorrent clients such as Vuze or BitComet. The program has received consistently good reviews for its feature set, performance, stability, and support for older hardware and versions of Windows.
The program has been in active development since its first release in 2005. Although originally developed by Ludvig Strigeus, since December 7, 2006, the code is owned and maintained by BitTorrent, Inc. The code has also been employed by BitTorrent, Inc. as the basis for version 6.0 and above of the BitTorrent client, a re-branded version of µTorrent.
µTorrent is available for Microsoft Windows, Mac OS X, Linux, and Android. A µTorrent Server is also available for Linux. All versions are written in C++.
Out of general discontent with bloatware, Serge Paquet suggested to Ludvig Strigeus that he should make a smaller and more efficient BitTorrent client. Strigeus began to conceptualize the plans for the program's development, which, at the time, did not include making the client feature-rich. After initially working on it for about a month during the last quarter of 2004 (the first build is dated October 17, 2004), mostly during his free time before and after work, Strigeus ceased coding µTorrent for a year. He resumed work on September 15, 2005, and three days later, the first public release (version 1.1 beta) was made available as freeware, and began generating feedback.
On March 4, 2006, PeerFactor SARL announced the signing of a six-month contract with Strigeus for the development of "new content distribution applications on the Web." PeerFactor SARL is a relatively new company formed by former employees of PeerFactor, which was a subsidiary of the French anti-piracy organization Retspan.
Ludde stated that his coding for PeerFactor SARL was to use his expertise at optimization of the BitTorrent protocol to create a .dll which PeerFactor SARL intended to use as part of a distribution platform for files in a corporate setting. At the time there was some speculation that μTorrent may have been modified to spy on users on Peerfactor's behalf, however to date (even following μTorrent's acquisition by BitTorrent, Inc.) no evidence has been produced to support these allegations.
On December 7, 2006, µTorrent was purchased by BitTorrent, Inc., as it was announced on their official forum.
On September 18, 2007, BitTorrent 6.0 was released, which is a re-branded version of µTorrent. As a result, BitTorrent 6 is closed-source (unlike BitTorrent 5.x and before, which were open source software).
Support for Magnet Links (URIs) was added in version 1.8, released on August 9, 2008. Magnet Links were designed as an alternative to traditional tracker torrent files and became popularized when sites such as The Pirate Bay included native support for the format.
Features present in µTorrent include:
µTorrent is shipped as a single stand-alone compressed executable file, installed at first run. Recent versions have included the ability to install themselves on first run. Small executable size is achieved by avoiding the use of many libraries, notably the C++ standard library and stream facilities, and creating substitutes written specifically for the program. The executable is then compressed to roughly half of its compiled and linked size using UPX.
µTorrent is available for Microsoft Windows, Mac OS X and Linux.
The first test version for Mac OS X, running on Mac OS X 10.5, was released on 27 November 2008.
On September 2, 2010, the native Linux version of µTorrent Server was released. Firon, an administrator of the µTorrent community forum, said that they had been working on this project for a few months prior to the release as it was the most requested feature for some time. This release is intended for users who are seeking a fast command-line interface based BitTorrent client with a remote web-based management. They also mentioned that a full featured client with a GUI is a work in progress. He also said: "This is a native Linux port and is known to work on Ubuntu 9.10+, Debian 5+ and Fedora 12+. Others may work, but they are not officially supported. Kernel 2.6.13 or newer required. 64-bit host systems currently have some problems, so 32-bit only for now. For trackers who whitelist, the user agent is "uTorrent/300B(build#)(server)". The peerid is identical to the Windows 3.0 client. They share version numbers because of a common codebase."
Currently μTorrent supports Windows XP or newer and Mac OS X 10.5 or newer
In early versions, Strigeus had built in a web redirection via nanotorrent for search queries entered through the search bar that displayed advertisements in a frame on the web browser. Some users thought this suspicious because tracking could be implemented by recording the IP addresses of those downloading/receiving the advertisements, and the search functionality could easily be used to track user queries through whichever web-interface the client is going through to execute the search. After a short trial period, the advertising was disabled, mitigating possible concerns.
A later version of the software has, instead of ads, a "search all sites" feature, which is a keyword-based search bar that delivers listings of torrent files at different trackers. A frame at the top displays advertisements (server-side) in the browser when the search function is used. In version 1.5, no ads are present in the program itself.
As of build 463, a redirect bypass feature became available in the Advanced options.
As of version 1.8.2, the µTorrent installer gives the user the option to download and install the Ask.com toolbar. This is done on the first run of the program and the user may explicitly opt out of this feature by deselecting it. The developers stated the addition was needed for funds to continue development. In late 2010, this was replaced with the Conduit Engine.
In late 2010, some controversy arose with a release of µTorrent which included adware in the form of the Conduit Engine, which installed a toolbar, and made homepage and default search engine changes to a user's web browser. A number of users reported that the installation was made without the user's consent. There were some complaints that the adware software was difficult to remove. In 2011, µTorrent bundled the Microsoft Bing toolbar.
On July 15, 2011, BitTorrent announced that they would offer a paid version of µTorrent called "µTorrent Plus". This new version would offer extra features, such as integrated file conversion, anti-virus and a built in media player. On 6 October 2011, the Pre-alpha of µTorrent Plus was released to an invite only community. As of December 2011, µTorrentPlus 3.1 Stable is now available for purchase and download.
In August 2012, BitTorrent announced the addition of advertising in the free version of µTorrent which could be individually dismissed by users. Due to response from users, a few days later, the company stated that ads could be optionally turned off. Starting from version 3.2.1 ads can actually be disabled manually from tools menu.
Starting with uTorrent version 3.2.2, the software also contains in-content advertisements described as "Featured Torrent". It is possible to disable the "Featured Torrent" by selecting Options>Advanced, searching for the parameter offers.sponsored_torrent_offer_enabled and switching the value to "False". The program must be restarted in order to remove the advertisement.
The author of µTorrent wrote in 2005, "I usually say 'you torrent' because it looks like a u", and offered "microtorrent", "mytorrent" (as "my" is the Swedish pronunciation of the Greek letter µ) and later "mutorrent" as alternate pronunciations.
The symbol μ is the lowercase Greek letter Mu, which stands for the SI prefix "micro-" meaning "one millionth"; it refers to the program's small footprint.
The traditional English pronunciation of the letter μ is /ˈmjuː/ (as in the English word 'mew'), derived from its Classical Greek pronunciation (impossible to represent accurately with "sound-alike" respelling, since English lacks the close front rounded vowel [y]). The corresponding Standard Modern Greek pronunciation is , much like the English word 'me'.
Original development was performed by Ludvig Strigeus ("ludde", from Sweden), the creator of µTorrent. Serge Paquet ("vurlix", from Canada) acted as release coordinator, and had intended to work on Linux and Mac OS X ports. He maintained the µTorrent website and forum up until the end of 2005, but is no longer affiliated with µTorrent.
Development after the purchase by BitTorrent is performed by developers Adam Kelly ("AdamK"), Arvid Norberg ("arvid", author of libtorrent), Greg Hazel ("alus"), Jan Brittenson ("CodeRed"), Richard Choi ("rchoi"), Ryan Norton ("RyanNorton") and Venkat Naidu ("naiduv") among others at BitTorrent Inc. Strigeus remains as a technical consultant.
Other tasks continue to be performed by ongoing contributors. Giancarlo Martínez ("Firon", from Puerto Rico) maintains the µTorrent forums and FAQ. Carsten Niebuhr ("Directrix", from Germany) developed the original µTorrent Web User Interface which is now maintained by "Ultima".
μTorrent has been praised for its small size and minimal computer resources used, which sets it apart from other clients. PC Magazine stated that it "packs an outstanding array of features" in 2006 and listed it in their 2008 "Best free 157 software tools". It was also in PC World's "101 Fantastic freebies". The website TorrentFreak.com said it was the most feature rich BitTorrent client available, later summarizing a 2009 University of California, Riverside study which concluded that "uTorrent Download Speeds Beat Vuze By 16%" on average and "on 10% of [the 30 most used] ISPs, uTorrent users were downloading 30% faster than Vuze users". About.com said it was the best BitTorrent client available, citing its small size and "minimal impact to the rest of your computer's speed." Wired.com said its "memory footprint is also ridiculously small". PC & Tech Authority magazine (Australia) gave it 6 stars (out of 6). Lifehacker.com rated it the best BitTorrent client available (Windows) in 2008 and 2011 (Windows and Mac). CNET.com gave it 5 stars (of 5) saying it features "light and quick downloading".
In November 2009 52 million users were reported to be using the application, and in late 2011, 132 million.
According to a study by Arbor Networks, the 2008 adoption of IPv6 by µTorrent caused a 15-fold increase in IPv6 traffic across the Internet over a ten-month period.
The software is available in the following languages: