Aria2 Download Manager

aria2 is a lightweight multi-protocol and multi-source command-line download utility that supports HTTP/HTTPS, FTP, SFTP, BitTorrent, and Metalink protocols with simultaneous connections for accelerated downloads. Developed by Tatsuhiro Tsujikawa since 2006, aria2 is widely used in download managers, scripts, and containers. Key features include: multi-protocol support (HTTP, HTTPS, FTP, SFTP, BitTorrent, and Metalink with automatic protocol detection and multi-protocol downloads within a single session), multi-connection download (split files into segments and download each segment simultaneously via multiple connections, configurable segment count and per-server connection limits for maximizing bandwidth), multi-source download (download from multiple URLs for the same file simultaneously via Metalink or multi-URI input, combining bandwidth from different mirrors), BitTorrent support (full BitTorrent client with DHT, PEX, magnet links, web seeding, selective file download, and peer exchange), Metalink support (download files from Metalink XML files containing checksums, multiple source URLs, and metadata for error recovery), RPC interface (JSON-RPC and XML-RPC over HTTP and WebSocket interfaces for programmatic control, enabling GUI frontends like AriaNg), configuration (aria2.conf configuration file with comprehensive options for proxy, authentication, download directory, and connection settings), session management (save and resume download sessions across restarts), checksum verification (verify downloaded files against checksums from Metalink or command-line specified hashes including MD5, SHA-1, SHA-256, and SHA-512), authentication (HTTP Basic and Digest auth, FTP user/password, SSH key authentication for SFTP), proxy support (HTTP and HTTPS proxy with per-protocol proxy configuration), and IPv6 support (dual-stack IPv4 and IPv6 downloads).