When most people hear the word 'BitTorrent', they don't tend to think 'Ah, yes, that indubitably fine way to download legitimate files'. Since its creation, though, the often-naughty protocol has been just as useful for legal file transfer, such as handling the grunt work in tools like Blizzard's World of Warcraft updater, and for letting creators share movies and games and other large files without having to foot a crippling bill.
BitTorrent's creators are also experimenting with 'bundle' content, with over 18 million legit downloads already clocked and a new publishing platform on the way. Obviously, this is the only kind of content you will be downloading.
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While the basic job of any BitTorrent client is pretty simple - click a torrent, sit back and wait - the apps we'll be looking at all put a very different spin on things. Tools range from open source to commercial products, from light apps that simply do their job to comprehensive media suites. But which one is best for you?
Malware and more: Careful when you click
BitTorrent clients don't have the greatest reputation, and while it's not as deserved on the Mac as on other platforms, they remain a bad type of product to simply download and give a shot. Even the legitimate ones routinely try to sneak toolbars and homepage changes past you through their installers, and every big update can be a new chance for them to give it a shot. In most cases these can be fixed with a sigh and a trip to your browsers' extensions menu, but it's still a nuisance and you're always left with the possibility of something quieter lurking around.
Before downloading any, it's worth doing a quick search of the name plus key terms like 'spyware' just to be on the safe side. A number of clients are 'open source' - in other words, you can download the code behind them. Despite what some people think, this doesn't guarantee a lack of naughtiness, but it does help.
Also, only ever download your clients from official sites/links, and make sure you're on the right one. Scammers aren't above repackaging clients and passing them off as the real deal, or picking up website addresses that look official until it's too late.
Test one: The basics
For when you just want that file now
Almost all of these apps do a fine job out of the box, with download speeds based more on the number of users accessing the file than anything else. Xtorrent is the exception; its free version caps downloads at 100kb/s after a few minutes and nags you for $25. With free alternatives and a lack of unique features, this is a tough sell. BitTorrent Plus is PC only. Vuze Plus adds antivirus for $19 a year.
All the apps offer a way to control how much uploading you do. BitTorrent (and uTorrent, which is very closely related) offers transfer capping. BitTorrent, Transmission, and Xtorrent offer the option to easily change limits automatically between set times, but vary on whether they treat it as a speed limiter or lifting normal restrictions.
Vuze offers this too, but configured by an oddly clumsy text file. After a download finishes, most clients prefer to keep seeding, and all offer controls for that - Tomato is the most comprehensive, offering a percentage, a maximum amount of data, or a set period of time.
Test two: Advanced options
Which client is best for power users?
Aside from Xtorrent, these apps can create torrents as well as download them - a process that's as easy as picking a file or a folder and optionally pointing the resulting torrent file to a tracker. That's where Tomato calls it a day, followed by BitRocket. BitTorrent and Transmission support remote access through a web browser, though for the latter you need a static IP address. BitTorrent offers a service that simply works across the internet.