When comparing qBittorrent vs aria2, the Slant community recommends qBittorrent for most people. In the question“What are the best Torrent clients?” qBittorrent is ranked 1st while aria2 is ranked 5th. The most important reason people chose qBittorrent is:
qBittorrent is available as free, ad-less software licensed under GPL with source code available on [GitHub](https://github.com/qbittorrent/qBittorrent/). Being open source allows anyone to check if the software has no malicious code, is secure and respects privacy.
Ranked in these QuestionsQuestion Ranking
Pro Free, ad-less and open source
qBittorrent is available as free, ad-less software licensed under GPL with source code available on GitHub. Being open source allows anyone to check if the software has no malicious code, is secure and respects privacy.
qBittorrent 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, web and command line interfaces. Has UPnP, NAT-PMP, NAT traversal for automatic router configuration. Has UDP tracker and µTP data transfer protocol support. Even covers Tracker Exchange, IPv6, web seeding, Embedded tracker, Super-seeding and proxy servers.
Pro Sequential downloading
Allows to download the first file of a series prior to the following items.
Pro Preload Magnet metadata
Obtain lists of files in Magnet before prompting the user for a download location.
Pro Auto torrent adding
Torrents can be automatically read from a folder.
Pro Enables streaming media while it's downloading
qBittorrent supports sequential downloading that allows users to download files in sequential order. That means that media such as video or audio can be streamed a the same way it can be with any other streaming service.
Pro Allows share ratio limiting
Can configure to what ratio (amount uploaded/amount uploaded) the torrent should be seeded. You can also configure on whether you want them to be paused or removed after this.
May also set this directly in the
[Preferences] Bittorrent\MaxRatio=2.5 Bittorrent\MaxRatioAction=0 # 0=Pause, 1=Remove
Pro Can be used to create torrents (embedded tracker)
qBittorrent can be used to create a torrent to share large files/folders with other people.
Pro Good web interface
The remote API and web interface works well. There is headless version too (called qbittorrent-nox).
Algorithm that helps downloaders to be able to become uploaders more quickly.
Pro Has a command line interface and a daemon
Can be run on a headless Linux (for text-only mode from the command-line without requiring X11). The package is commonly named qbittorrent-nox (and it's officially supported by qBittorrent).
Pro RSS support
Add RSS feeds for automatic downloading. Apply filters to only download what you want.
Pro Tracker exchange
Makes it possible for BitTorrent peers to learn about new trackers for a swarm they have joined. Ideally ending up with every peer knowing about every tracker used for the torrent
Pro IP filtering
IP filtering blocks set IP addresses. It's usually used to block communications with certain companies that are against p2p activity, etc.
Pro In-Program torrent search via various search-engines
Pro Supports multiple download protocols
Has support for lots of download protocols including BitTorrent, Metalink, HTTP, HTTPS and FTP.
Pro Small memory footprint
Due to aria2 being a CLI only tool it uses very little memory.
Pro Free and open source
Pro Remote control over simple standartized RPC
XML or JSON-based RPCs can be used to control aria2 remotely with both APIs completely documented. Simplest client that uploads torrent to be downloaded is 3 Python lines long (no 3rd-party libraries, only stdlib).
aria2c --help=#rpc to see more.
Pro Third parties offer a clean web interface
Some web interfaces consist of pure HTML+JS, no server-side needed (except aria2c of course). It uses the same RPC that can work even over WebSockets.
Con Has issues with large torrent numbers
Various issues occur with large torrent numbers (anywhere between 300 and 1000 torrents) including timestamp and file corruptions.
Con Old UI
Looks a bit ugly.
Con Torrent downloads can freeze
Multiple people have reported that torrents stop downloading and stay in a "stalled" state indefinitely.
Con Search engine requires installing Python
Con Needs to be reinstalled from time to time
Sometimes it just stops downloading, the fix is uninstalling and installing again. It's a pain, but ends up working.
Con Constant IO error
Con No native graphical user interface
While there is a web-based GUI, there is no native interface.