µTorrent Icon
µTorrent Screenshot
µTorrent 2.0 in Windows 7
Original author(s)Ludvig Strigeus
Developer(s)BitTorrent, Inc.
Initial release18 September 2005
Written inC++
Operating systemMicrosoft Windows; Mac OS X 10.5 (Intel and PPC); Wine (Linux) officially supported
Available in52 languages
Development statusActive
TypeBitTorrent client
LicenseProprietary freeware

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From Wikipedia, the free encyclopedia

µTorrent (or uTorrent and commonly abbreviated as "µT" or "uT") is a freeware, closed source BitTorrent client by BitTorrent, Inc. It is available for Microsoft Windows and Mac OS X. Both versions are written in C++. It gets the "µ" in its name from the SI prefix "micro" meaning one one-millionth and it refers to the program's small footprint. The program is 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. A report showed that µTorrent is the second most popular BitTorrent client (after the Chinese Xunlei).

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 of the BitTorrent client, a re-branded version of µTorrent.

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.


µTorrent is shipped as a single stand-alone compressed executable file, and does not require installation through an installer, which is available for trivial installation. 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.


Early development

Out of general discontent with bloatware, Serge Paquet suggested to Ludvig Strigeus that he should make a small and 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.


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.

PeerFactor SARL

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.

Ownership change

On December 7, 2006, µTorrent was purchased by BitTorrent, Inc., as it was announced on their official forum. µTorrent will continue to have its own website and community for now, and the µTorrent code base will remain closed source. Ludvig Strigeus, the writer of µTorrent, will serve as a technical consultant, but BitTorrent, Inc. will do the majority of the development work.

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) and is currently only available for Windows.

Release history

VersionSizeRelease date
1.0.077 kB kB2005-10-22
1.2.2107 kB2005-11-25
1.3.0115 kB2005-12-10
1.4.2142 kB2006-01-11
1.5.0155 kB2006-03-08
1.6.1173 kB2007-02-15
1.7.7214 kB2008-01-25
1.8.5282 kB2009-10-29
2.0.0311 kB2010-01-25
2.0.2314.8 kB2010-05-13

Mac version

A separate version of µTorrent for Mac OS X 10.5 (commonly abbreviated as "µMac") has been in development for years. As of November 27, 2008 a beta version (Intel x86 and PPC) is available for download on a separate section of the website.

Ask.com toolbar

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.


The author of µTorrent wrote in 2005, "I usually say 'you torrent' because it looks like a u", and offered "microtorrent", "mytorrent"(as "my" [myː] is the Swedish pronunciation of the Greek letter µ) and later "mutorrent" as candidate pronunciations. The symbol μ, which is actually the small Greek letter Mu, stands for the SI prefix "micro" meaning one one-millionth and refers to the program's small footprint.

About box easter eggs

  • If the user opens the About screen ("Help" > "About µTorrent") and then presses the "T" key, it will start a built-in tetris game called µTris.
  • Clicking the µTorrent logo in the About screen will play a synthesized sound similar to Deep Note.


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 Greg Hazel ("alus"), Arvid Norberg ("arvid", author of libtorrent), Jan Brittenson ("CodeRed"), Richard Choi ("rchoi") and Ryan Norton ("RyanNorton") 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 and maintains the µTorrent Web User Interface. Timothy Su ("ignorantcow", from Malaysia) is the designer of the current website.


μTorrent is praised for its small size and the minimal computer resources it uses which sets it apart from other clients. PC Magazine gave the program a positive review saying that it "packs an outstanding array of features". and was also listed in their Best free 157 software tools. It was also in PC World Magazine's 101 Fantastic freebies. The Manila Standard Today said it is the "hands-down best utility for downloading large files in Windows". The website TorrentFreak.com said it was the most feature rich BitTorrent client available, later summarizing an August 2009; 8 months ago (2009-08) 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". The PC Authority magazine gave it a 6 out of 6 stars. Lifehacker.com has continued to rate it the best BitTorrent client available. CNET.com gave it a 5 out of 5 stars saying it features "Light and quick downloading".

Other popular applications that can open .TORRENT files

  1. Downloadµtorrent

    License: Free
    Operating system: Win 7, Vista, XP, NT/2000, 2003, Wine, (32-bit and 64-bit editions of Windows supported)

  2. InfoBitorrent