Please read the following regarding Avalanche's future

avalanche-rt is a web based front end for rTorrent. avalanche-rt provides a friendly frontend, loosely based on Clutch (Transmission's web interface).

rTorrent is a command line BitTorrent client, for use on Linux systems, including servers, seedboxes and Linux based devices such as a dd-wrt router.

If you would like to purchase a seedbox I fully recommend RapidServerz for good quality, fast seedboxes!

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Features

Able to list, sort and filter torrents loaded into rtorrent
Start & stop torrents, rename them, change the priority & assign labels
Bulk start/stop torrents, using Ctrl, Shift to select a range of torrents, or "Resume/Pause All"
View detailed information, such as peers, trackers, files
Prioritise files in a torrent, and disable trackers
Set upload and download rates
Upload a torrent (via URL) directly to rtorrent
Built in web search allows you to search your favourite torrent sites straight from the gui
Built in filter bar allows you to quickly search among your torrent list.
Very shortcut friendly, able to stop/start/rename torrents, use the web and filter bars, and set upload/download rates all from the keyboard.

Requirements

A computer or device with Linux installed (usually a server, or appliance such as dd-wrt router)
rtorrent installed or compiled with XMLRPC support, which is enabled (if you're using the Ubuntu package, this is sufficient)
A web server (such as apache or lighttpd) which supports both SCGI and PHP.