aria2 is a lightweight multi-protocol & multi-source command-line download utility. It supports HTTP/HTTPS, FTP, SFTP, BitTorrent and Metalink, etc.
License: Open Source
Aria2 is a free and open-source download manager that excels in customization and supports multiple protocols, making it suitable for tech-savvy users. In contrast, Internet Download Manager (IDM) is a paid software known for its user-friendly interface and advanced features, making it ideal for users who prefer a more straightforward and feature-rich downloading experience.