aria2

Aria2 是一个多平台轻量级，支持 HTTP、FTP、BitTorrent 等多协议、多来源的命令行下载工具。Aria2 可以从多个来源、多个协议下载资源，最大的程度上利用了你的带宽。Aria2 有着非常小的资源占用，在关闭磁盘缓存的情况下，物理内存占用通常为 4M（正常 HTTP/FTP 下载的情况下），BitTorrent 下载每秒2.8M/S的情况下，CPU 占有率约为 6%。Aria2 支持 JSON-RPC 和 XML-RPC 接口远程调用。

很多人在 Windows 可能用过 Internet Download Manager，是很好用的多线程下载工具。Aria2 跟 IDM 类似，不仅可以多线程下载，还可以通过多来源进行下载，简单的说就是从多个镜像服务器同时下载一个文件，Aria2 还支持 BT 协议，弥补了 IDM 只支持 HTTP 和 FTP 的痛点。

Linux下的软件截图：

Windows 下的软件截图

特性：

• Command-line interface
• Download files through HTTP(S)/FTP/SFTP/BitTorrent
• Segmented downloading
• Metalink version 4 (RFC 5854) support(HTTP/FTP/SFTP/BitTorrent)
• Metalink version 3.0 support(HTTP/FTP/SFTP/BitTorrent)
• Metalink/HTTP (RFC 6249) support
• HTTP/1.1 implementation
• HTTP Proxy support
• HTTP BASIC authentication support
• HTTP Proxy authentication support
• Well-known environment variables for proxy: http_proxy, https_proxy, ftp_proxy, all_proxy and no_proxy
• HTTP gzip, deflate content encoding support
• Verify peer using given trusted CA certificate in HTTPS
• Client certificate authentication in HTTPS
• Chunked transfer encoding support
• Load Cookies from file using the Firefox3 format, Chromium/Google Chrome and the Mozilla/Firefox (1.x/2.x)/Netscape format.
• Save Cookies in the Mozilla/Firefox (1.x/2.x)/Netscape format.
• Custom HTTP Header support
• Persistent Connections support
• FTP/SFTP through HTTP Proxy
• Download/Upload speed throttling
• BitTorrent extensions: Fast extension, DHT, PEX, MSE/PSE, Multi-Tracker, UDP tracker
• BitTorrent WEB-Seeding. aria2 requests chunks more than piece size to reduce the request overhead. It also supports pipelined requests with piece size.
• BitTorrent Local Peer Discovery
• Rename/change the directory structure of BitTorrent downloads completely
• JSON-RPC (over HTTP and WebSocket)/XML-RPC interface
• Run as a daemon process
• Selective download in multi-file torrent/Metalink
• Chunk checksum validation in Metalink
• Can disable segmented downloading in Metalink
• Netrc support
• Configuration file support
• Download URIs found in a text file or stdin and the destination directory and output file name can be specified optionally
• Parameterized URI support
• IPv6 support with Happy Eyeballs
• Disk cache to reduce disk activity