aria2 is a lightweight multi-protocol & multi-source, cross platform download utility operated in command-line. It supports HTTP/HTTPS, FTP, BitTorrent and Metalink.
aria2 has built-in XML-RPC interface. You can manipulate aria2 via XML-RPC interface.
aria2 runs on Linux, FreeBSD, Mac OS X and Windows.
aria2 can download a file from multiple sources/protocols and tries to utilize your maximum download bandwidth. Really speeds up your download experience.
aria2 doesn't require much memory and CPU time. The physical memory usage is typically 4MiB (normal HTTP/FTP downloads) to 9MiB (BitTorrent downloads). CPU usage in BitTorrent with download speed of 2.8MiB/sec is around 6%.
All features you want in BitTorrent client are available: DHT, PEX, Encryption, Web-Seeding and Selective Downloads.
aria2 supports the advanced feature of Metalink v3.0. File verification, Multi-file metalink, HTTP/FTP/BitTorrent integration and Configuration for language, location, OS, etc.
Command-line scares you off? No, aria2 is really easy to use!!
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.