Best Free BitTorrent Client

It's amazing how quickly Bittorrent (What is Bittorrent?) has become one of the major download formats. With good reason too: it's fast, equitable and efficient. If you haven't yet installed a Bittorrent client on your PC, you should as there are some great free clients available.   In Bittorrent the best clients are free.  (In fact, if a client costs money, it is most likely a scam)

I tested ten bittorrent clients for speed and all ten, after proper setup, ran at essentially the same speeds.  Given their equal performance the decision on which is best was based primarily on support and features.  Other than Miro and Halite, clients had low CPU use.  The amount of RAM use by these clients varies greatly, but with the amount of RAM that the average user has on their system nowadays, that is not much of an issue.   The RAM use on my computer is noted here for your reference.  The use on your computer may vary, but these client's use of RAM relative to each other should be in line with my numbers.  I have linked to screen shots of the Top Picks and Other Suggested Clients as the interface of these clients may be a factor in your decision of which to use.

The features that I considered were first the basic ones that every user would want, Encryption (helps with ISPs that interfere with bittorrent); UPnP and NAT-PMP support (automatically configures compatible routers); Selective Downloading (allows downloading of specific files inside a torrent); and DHT and PEX (support trackerless torrents and help to find more peers).   Other features that some users may want are RSS, remote control, and bandwidth allocation (allows more bandwidth to be given to a torrent; helpful for those who use private trackers).  Those who  publish torrents should also look for a (built in) tracker and super seeding.

Top Picks

These four clients are well above the average bittorrent client.  I would call it a tie for best between µTorrent and Vuze.  µTorrent is a basic client that is extremely efficient and Vuze is full featured.  Transmission and BitComet come in close behind.  Transmission as a lightweight client for Mac and Linux users and BitComet as a relatively lightweight client that is useful for traversing troublesome networks.

My personal favorite is Vuze (formerly Azureus).   Azureus was always well known for its informative interface and wide variety of plugins due to its being open source.  Now it has added the Vuze patform which provides a large and growing amount of legal content for download.  Most of the content is free and downloads at maximum speed as it is also supported by Vuze servers.  The 3.1 series introduced the Friends plugin, which allows for secure and encrypted sharing.  Vuze has all of the features discussed above and more.  Basically Vuze has all the bells and whistles you could want.  In spite of adding the Vuze platform and other features over the past two years, the Vuze developers have significantly reduced the amount of Vuze's RAM usage.  Still its RAM use (60,000K) is at the high end of these clients.  Vuze is cross platform and has excellent support at its Azureus-Wiki,  Vuze forums and Vuze FAQ.

The most popular bittorrent client now is µTorrent.  Quite impressive as a short time ago they were acquired by BitTorrent, Inc. and were tainted by BitTorrent's association with the media industry.  Equally impressive is the list of features that this tiny program has.  Like Vuze it has all the features above, but is also the smallest and easiest on system resources (1,000K RAM) of any bittorrent client.  µTorrent  has gained popularity because it does the basic downloading of torrents as well as any client and does it more efficiently than any other client.  µTorrent is essentially a Windows only application, but can be run on Mac (Intel) and Linux with Wine (guide).  µTorrent's FAQs, guides and forums make for excellent support.
Note:  Secunia has released a "critical vulnerability" alert for µTorrent 1.7.7 (Build 8179) and earlier builds, which has been patched in version 1.8.  An upgrade to 1.8 is suggested.   This is the second "highly critical" alert that Secunia has issued for µTorrent this year.  µTorrent  responded quickly to the alert, issuing a fix in the 1.8 version.  Although this alert was not enough for me to remove µTorrent from this list, I would point out that none of the other clients suggested here has ever had a "highly critical" security alert issued by Secunia.

For those with Mac or Linux looking for a lightweight client I would suggest Transmission.  I have not used this client myself, but it has uniformly received positive reviews for being full-featured but easy on system resources.  It has also been chosen as the default bittorrent client for Ubuntu. The support is not at the level of Vuze or µTorrent, but their forums appear to be well frequented by Transmission developers.   Transmission is missing a few features, such as DHT, RSS, super seeding and a built in tracker.

BitComet is a Windows only client that is missing remote control, but has the other features above and uses a small amount of memory (3,000K).  The primary reason for its inclusion as a top pick is that some users have reported that it is able to get through some networks (schools etc.) that other clients cannot.  BitComet also has a "media preview" feature that allows preview of the content before the download is finished (this will slow download speed ) to help avoid wasting bandwidth on fakes or poor quality content.  Their forums are well maintained and their blog provides some guides, making for decent support.
Note Bitcomet does have its issues with the bittorrent community.  It has a reputation as a "bully" client and at one time was banned at most private trackers (more private sites are now allowing Bitcomet's newer releases).   Robb Topolski (who first verified Comcast's bittorrent interference) debunked most of these issues (at least for newer versions) in this article.  However, there is still an issue with its super seeding, causing the BitTornado developer (John Hoffman, who created super seeding) to ban Bitcomet users from connecting to BitTornado users.  Topolski also states that Bitcomet does have issues when it is the original seed for a torrent.

Other Suggested Clients

There are a number of other free bittorrent clients that work well.  The following are clients that work well, but do not rise to the level of the Top Pick clients above.  Still, they download as well as any client and some users may prefer their interfaces.  I have linked to their sites, rather than the more desciptive anchors here for the Top Picks, to keep this review to a reasonable length.

BitTornado is a cross platform client that is mssing some features, PEX, DHT, RSS and remote control and has a high memory use (33,000K, at least on Windows) for a fairly basic client.  Its forums are well maintained, with much input from the developer, but its FAQ is a bit weak. (Screenshot)

Deluge is a cross platform client that is missing the super seeding and built in tracker features, but has the rest of the features above.  Its memory use (40,000K) is high for a basic client.  Its forums are not that active, but are well maintained.  Its FAQ also has some support info. (Screenshot)

BitTyrant is an Azureus 2.5 knockoff that is supposed to deliver better speeds by slightly violating the bittorrent protocol.  I did not find it any faster than the others here in my tests.  Its memory use (42,000K) is better than Vuze, but its lack of updates and support (the Azureus-Wiki will help for many issues) kept it from being a top pick.  It is missing the newer features of Vuze, but has all the features discussed above.  It is a cross platform client.  There is no support from the BitTyrant developers.  BitTyrant is banned at most private trackers. (Screenshot)

Clients That Are Not Suggested

I am listing these clients as they were brought up in comments here and are at times mentioned at the various bittorrent forums that I frequent.

Frostwire is a cross platform Gnutella/Bittorrent mix.  Although it ran well in my speed tests, its lack of basic bittorrent features and relatively high memory use (42,000K) make it a non-choice.  For those who primarily use Gnutella and occasionally bittorrent, it is an acceptable choice, but not as a bittorrent client only.

BitTorrent would have made at least the suggested client list, but for the fact that a "highly critical" security alert was issued for it on 8/12/2008 (the second this year) by Secunia and this vulnerability remains unpatched.  BitTorrent is the µTorrent client repackaged under the BitTorrent name with the extra baggage of DNA.  DNA does nothing for the average user and is constantly running (even when BitTorrent is closed).  Removing DNA makes BitTorrent as efficient as µTorrent, but it makes more sense to just get µTorrent.  On 8/16/2008 BitTorrent released version 6.1, which is identical to the uTorrent 1.8 which patched this security flaw.  However Secunia does not show this flaw patched yet for BitTorrent.

BitSpirit is hard to figure out.  Its website is listed as red (bad) by McAfee Site Adviser and the latest version there is from 2005.  However, FileForum's download for it shows a release date of August, 2008.  BitSpirit is based upon an old BitComet code and as a result is banned at some private trackers.  It does have the media preview and also will traverse some networks that other clients cannot (as BitComet does).  However, BitComet in its updated state is probably a better choice.

ABC is based upon BitTornado and has better memory use (20,000K), but it has not been updated since 2005 and that means it is missing many of the newer features of bittorrent.  It is banned at some private trackers.

BitLord is also based upon the old, buggy Bitcomet code and is banned at some private trackers.  While it also has the positive of traversing troublesome networks well, it has not been updated since 2005 and BitComet is a better choice for dealing with those networks.

Opera is a browser that supports bittorrent.  It lacks many features and from what I have read adds 5,000K in memory use to the browser.  That makes both µTorrent and Bitcomet better choices as basic bittorrent clients.

These last two clients caused severe CPU issues on my Windows XP SP3 system.  I am not sure why and have not seen this issue mentioned before with these clients.  I cannot fully evaluate them because of this. 

Halite is a Windows only client that is missing a number of features, PEX, RSS, remote control, super seeding and built in tracker.  Its memory use (7,000K) is on the low end, but not as efficient as the lighter Top Picks.  Their forums are well maintained, but other support is lacking.   With no CPU issues, this may not be a bad choice.

Miro is an intrernet TV and video player that supports bittorrent.  Its high memory use (96,000K) and lack of features make it a non-choice as a bittorrent client even with no CPU issues.

A good listing of bittorrent clients that have some issues and that are banned at private trackers (at least some) is at  Mystery Axiom Forums. 
There are also some bittorrent clients that contain malware and should be avoided.  They are listed at leechermods.

There are guides for getting the best download speed for each of the Top Pick bittorrent clients above, here at Gizmo's Tech Support Alert:

• Optimizing Vuze (formerly Azureus) For Speed  (applies to any version of BitTyrant or the prior Azureus versions)
• Optimizing  µTorrent for Speed  (applies to BitTorrent 6.1)
• Optimizing the Transmission Bittorrent Client for Speed
• Optimizing BitComet for Speed

After you have installed your bittorrent client and have set it up, you might want to check my articles

• Searching for Torrents (Popular Torrent Search Sites) for a listing of the most popular torrent search sites and their features.
• Finding Legal (and Free) Torrents which lists, with comments, sites that offer only legally downloadable and distributable content.

Comments on this article can be made below or in the forums.

Product Details

Vuze
Website:  http://www.vuze.com/app
Download link: http://azureus.sourceforge.net/download.php
Author: Olivier Chalouhi (Gudy)
Version: 3.1.1.0
Date: July 1, 2008
Download file size: 8.63 MB
License: Free under GNU General Public License (GPL)
Operating systems supported: Any PC that supports Java
64 Bit version available: No, but this 32 bit program works in a 64 bit environment
Portable version available: Unknown
Other languages supported: Many - see here: http://azureus.sourceforge.net/index.php
Additional software required: Java 1.6

µTorrent
Website: http://www.utorrent.com/
Download link: http://www.utorrent.com/download.php
Author: BitTorrent, Inc. (Originally: Ludvig (Ludde) Strigeus)
Version: 1.8 (Build 11813)
Date: August 13, 2008
Download file size: 260 KB
License: Freeware (Closed Source)
Operating systems supported: Wine, Windows 95 (Winsock2), 98/ME, NT/2000, XP, 2003, Vista
64 Bit version available: No, but this 32 bit program works in a 64 bit environment
Portable version available: Yes. See µTorrent FAQ:  How can I use µTorrent on USB key or other removeable drive?
Other languages supported: Many - see here: http://www.utorrent.com/download.php
Additional software required: No

Transmission
Website: http://www.transmissionbt.com/index.php
Download link: http://www.transmissionbt.com/download.php
Author:  Eric Petit
Version: 1.32
Date: August 9, 2008
Download file size: 3.24 MB
License: Free under GNU General Public License (GPL) and MIT License
Operating systems supported: Mac OS X 10.4.11 or later, Ubuntu GNU/Linux
64 Bit version available: Unknown
Portable version available: Unknown
Other languages supported: Many. See website link above
Additional software required: None

BitComet
Website:  http://www.bitcomet.com/  
Download link:  http://www.bitcomet.com/doc/download.htm
Author:  Comet Network Technology Co. Ltd.
Version:  1.03
Date:  July 17, 2008
Download file size:  5.24MB
License:  Free for non-commercial use (at home)
Operating systems supported:  Windows 2000/XP/2003/Vista
64 bit version available:  Unknown
Portable version available:  Yes See http://www.portablefreeware.com/?id=353
Other languages supported:  Many http://blog.bitcomet.com/post/407/
Additional software required:  No

This article was updated on August 15, 2008.