In search for the most stable yet low resource consuming download accelerator for my Raspberry Pi NAS, we have tested and written about excellent utilities like Transmission Bittorrent Client, pyLoad and FatRat which gets the job done. However, after extensive testing with all these I can now easily conclude that the best download manager for Raspberry Pi (or any other low-resourced Linux computer) is - aria2.

aria2 is an versatile multi-platform, multi-protocol download accelerator with lots of powerful features not available in any of the competing applications like the ability to download the same file from multiple URLS and protocols. Aria2 is available for Linux, Windows and Mac and supports multi-protocol, multi-segmented parallel accelerated downloads from HTTP,HTTPS,FTP,BitTorrent and Metalink protocols with download resume capability. Despite being a lightweight command line utility, you won't feel the lack of an GUI as it supports an XML-RPC interface for remote-control - there are quite a few handy GUI's available like web-interfaces, desktop clients and native mobile applications.