aria2

Port of aria2 for Android with builtin front-end (aria2-webui). Allows Android users to starts, configures and controls aria2 BitTorrent client via user-friendly graphical interface.

This is an unofficial Android port of powerful command line BitTorrent client aria2. aria2 is a lightweight download utility – with footprint of ~4Mb and about as much of Java overhead, specific to this port. It supports everything, one expects from modern torrent downloader: selective file downloading, prioritizing chosen file segments (e.g. watching film while downloading it) and much more. See site of the desktop version for further details: http://aria2.sourceforge.net
This application is NOT yet another Android remote control for desktop BitTorrent client! It embodies actual binaries of aria2, built for ARM and x86 with support for variety of Android versions, ICS and Lollipop included (if you see this text, your device is supported).
Note, that you DO need a frontend (e.g. remote control app) to download torrents with this port. All it does is launching aria2 binary with sensible parameters in user-friendly way; scheduling and controlling downloads have to be done by another app. For this you can choose between variety of third-party aria2 clients, developed by enthusiasts. I recommend Transdroid (free remote control app for large number of BitTorrent clients: https://play.google.com/store/apps/details?id=org.transdroid.lite), but you can also try to some other client (not tested by me yet, please write me if you are able to get any results with them):
* https://github.com/tsekityam/Aria2-Remote-for-Android
* https://github.com/binux/yaaw
UPDATE: a patched version of another web frontend — aria2-webui — have been bundled with apk. It can be used from built-in WebView (on Android versions, that provide decent up-to-date WebView) or unpacked to outside location and used from system browser. You may want to visit https://github.com/ziahamza/webui-aria2 for support and new versions of this frontend. If you use new versions from there, beware of https://github.com/ziahamza/webui-aria2/issues/193 — "outrageous CPU usage" bug, which has been patched in version here.
The app does not prevent device from sleeping by default! During device sleep all downloads are greatly slowed and will most likely timeout. To prevent this you can check "Take wakelock" checkbox below the "Start aria2" toggle. If you do so, make sure to stop aria2 when downloads complete, or you battery will discharge quickly. A better solution will be provided in future.
If you want to use one of advanced features of aria2, you can try to edit it's configuration file (named aria2.txt, stored in the same directory as downloaded files). Consult aria2 manual for additional details on the matter: http://aria2.sourceforge.net/manual/en/html/index.html
WARNING: out of security considerations aria2 RPC control is accessible only from localhost! To access aria2 over network, check "Allow external access" checkbox below the "Start aria2" toggle. Make sure to set up a secure password in settings before you do so!
If you encounter any issues (aria2 does not start, does not download etc.), consider using Terminal Emulator integration (Frontend section).
If you managed to read this far (congrats!!!), please take care to report all issues with this port to Github bug tracker: https://github.com/Alexander--/aria2-android/issues. All general issues with aria2 (e.g. "I was banned from the tracker X, because of Y") should be reported to aria2 bug tracker: https://github.com/tatsuhiro-t/aria2/issues Please DO NOT complain here about bugs and missing features in aria2 frontends; instead directly contact authors of those frontends.
Help to translate this project on Transifex: https://www.transifex.com/projects/p/aria2-android.
Please remember, that this is free as in freedom software, entirely developed by enthusiasts.
aria2 is free software, distributed under terms of GNU GPL. See https://github.com/Alexander--/aria2-android/ for a way to get the source code.
"BitTorrent" is a trademark of BitTorrent Inc.
Do not use this software to steal from others, use it to share!

Error logging bugfixes
Network interface selection support.
Allow setting rpc-listen-all from UI
Basic wakelock support
Ask for storage permission if not granted
Public broadcast receiver with support for for 3 intents: net.sf.aria2.service.START_SERVICE, net.sf.aria2.service.STOP_SERVICE and net.sf.aria2.service.RESTART_SERVICE. Should make it possible to script aria2 with Tasker and similar software.