aria2 is a lightweight multi-protocol & multi-source command-line download utility. It supports HTTP/HTTPS, FTP, SFTP, BitTorrent and Metalink. aria2 can be manipulated via built-in JSON-RPC and XML-RPC interfaces.

To run aria2 as an RPC server (without security!):

aria2c --enable-rpc --rpc-listen-all=true --rpc-allow-origin-all

To run aria2 with parameters on a config file (aria2.conf):

aria2c --conf-path=aria2.conf

Options in your config file:

To save downloads list so every time we restart aria2 resume downloads:--save-session=aria2sessionfile
--input-file= aria2sessionfile #must be same as save session

Continue downloading a partially downloaded file if a corresponding control file exists.
--continue=true
Store the downloaded file(s) in folder.

--dir=Downloads

Do not pre-allocate disk space before downloading begins

--file-allocation=none

AriaNg

AriaNg is a modern web frontend making aria2 easier to use. AriaNg is written in pure html & javascript, thus it does not need any compilers or runtime environment. You can just put AriaNg in your web server and open it in your browser. AriaNg uses responsive layout, and supports any desktop or mobile devices.