When comparing Transmission vs µTorrent, the Slant community recommends Transmission for most people. In the question“What are the best Torrent clients?” Transmission is ranked 2nd while µTorrent is ranked 23rd. The most important reason people chose Transmission is:
Transmission is free, ad-less and open source software licensed under GPL with parts under MIT with source code available [here](https://trac.transmissionbt.com/browser/trunk). Being open source allows anyone to check if the software has no malicious code, is secure and respects privacy.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free, ad-less and open source
Transmission is free, ad-less and open source software licensed under GPL with parts under MIT with source code available here. Being open source allows anyone to check if the software has no malicious code, is secure and respects privacy.
Pro Very lightweight
Transmission-gtk uses only 17 mb of RAM in idle state and 24 mb in download state.
Pro Very minimalistic, straightforward design philosophy
Transmission is great for getting things done without looking too much under the hood. It still has advanced options, they're just tucked away from sight.
Pro Native Mac, GTK+ and Qt interfaces provide seamless integration with OSX and Linux systems
Transmission works well on OSX and various distributions of Linux due to having interfaces natively developed for those operating systems instead of haphazardly ported.
The Mac interface is written in Objective-C, uses dock badges and Growl notifications while the GTK+ interface follows GNOME Human Interface Guidelines and has support for popup notifications, desktop sounds, and a system tray.
There's also an unofficial port of Transmission-Qt for Windows.
Pro Full-featured
Transmission covers basics such as Prioritization, Selective Downloading, DHT, PEX, LPD and Magnet URIs. It has graphical, web and command line interfaces. It includes MSE/PE for security. Has UPnP, NAT-PMP, NAT traversal for automatic router configuration. Has UDP tracker and µTP data transfer protocol support. Even covers IPv6, Web seeding and Local Peer Discovery. And it auto-updates.
Pro Has a command line interface and a daemon
Transmission can be used in text-only mode via transmission-cli
that includes a daemon (transmission-daemon
), a CLI and a web client (accessed on http://localhost:9091 by default).
Pro Works great on a seedbox with its web interface
Transmission has a web interfaces that can be used to remotely control torrents. It's great as a seedbox (a dedicated private server for uploading and downloading content) due to built-in webseed support.
Pro Pre-installed on multiple Linux distributions, including Ubuntu
For those who prefer Linux, the Ubuntu OS comes with Transmission already installed, so you can get your torrents up and running immediately.
Pro Headless software
Just put it on your server, SBC or even your old phone and you have your own torrent server.
Pro Lightweight
Weighs just barely over 1MB. And while it's gained a bit of feature creep over the years, it's still a lighter-weight client than many of its competitors.
Pro Full-featured
µTorrent covers basics such as Prioritization, Selective Downloading, DHT, PEX, LPD and Magnet URIs as well as Broadcatching, Sequential downloading and Search. It includes MSE/PE for security. It has graphical and web interfaces. Has UPnP, NAT-PMP, NAT traversal for automatic router configuration. Has UDP tracker and µTP data transfer protocol support. Even covers IPv6, web seeding, Embedded tracker, Super-seeding and proxy servers. And it auto-updates.
Pro Clean and easy to navigate user interface
A clean, visually-appealing interface that’s incredibly simple to navigate and cuts down on clutter by allowing any element of the UI not needed to be hidden.
Pro Doesn't slow down other Internet activities
The application automatically manages bandwidth it takes up to not get in the way of other Internet-dependent activities.
Pro Portable
µTorrent can be run without having to be installed as it stores all files and settings in the same folder. It can be put on an external storage device (such as a USB drive) and run directly from it.
Pro Built-in search
Built-in search engine allows finding torrents to download right from withing the torrent client.
Pro Cross-platform
µTorrent is available on Windows, Mac, Linux and Android.
Cons
Con No preload magnet metadata
Transmission is unable to preload magnet metadata.
Con If data is corrupted, torrent file has to be re-added
If you delete a file that belongs to (finished or not) torrent, torrent will remain in "corrupted data" state and only way to restore it (aside from restoring the actual data file) is to find the original file and re-add it.
Con No broadcatching support
Broadcatching is a method of automatically downloading content as soon as it's available. Broadcatching in BitTorrent clients is usually implemented via RSS. Transmission requires manually selecting each download.
Con No super-seeding support
Super-seeding is an algorithm used to allow downloaders become uploaders quicker. Transmission lacks support for this functionality.

Con The app is hiding too much information
While the app is clearly going for minimalism, some users might feel that the default window that consists of just torrents and their progress bars might provide a bit too little information or functionality. For example, even accessing file lists requires opening up a separate window and navigating to a specific tab.
Con No tracker exchange
Tracker exchange functionality allows peers to exchange information about trackers of a given file. It is another way of ensuring that the file is downloaded from the optimal source. Transmission lacks this functionality.
Con No embedded tracker
An embedded tracker allows turning the client into a server offering an easy way of sharing files with others. Transmission lacks embedded tracker support so another method of sharing or different client has to be used to share files.
Con Written in Python, uses a lot of CPU on fast downloads
Apparently, the speed bottleneck is Python.
Con No built-in search engine
Built-in search engines allow finding torrents to download right from withing the torrent client. Transmission lacks such functionality.
Con No proxy server support

Con Proprietary
No source code is publicly available. As such there's no way to independently check what security and privacy features are implemented and how as well as whether there's any malicious code or not.
Con No tracker exchange
Tracker exchange functionality allows peers to exchange information about trackers of a given file. It is another way of ensuring that the file is downloaded from the optimal source. µTorrent lacks this functionality.
Con Are known to bundle riskware
In additional to typical toolbar and ad bundles, µTorrent has previously bundled an automatic cryptocurrency-miner called EpicScale even if the user opted out of other bundled software.
Con Inappropriate ads (can be disabled)
Not only does μTorrent have ads in the free version, they tend to be inappropriate ads for scammy things like "meet russian women".
Ads can be disabled in the options. It's important to note that disabling ads (as well as all bundled software and featured content) can be a difficult process as it requires manually editing multiple key/value pairs in advanced settings.
The following keys have to all be turned to false by going to options > preferences > advanced:
bt.enable_pulse
distributed_share.enable
gui.show_notorrents_node
offers.left_rail_offer_enabled
gui.show_plus_upsell
offers.content_offer_autoexec
offers.sponsored_torrent_offer_enabled
offers.featured_content.badge.enabled
offers.featured_content_notifications_enabled
offers.featured_content_rss_enabled
Con Bundles bloat
Installation wizard starting with version 3 offers installing a variety of garbage features including toolbars and ads. And makes the process of opting out of such bundled software difficult. It's possible to find version 2.2.x online (1,2) - same lightweight, feature packed application without all the unneeded extras or ads.
