downloaders

A downloader is software that retrieves data from remote servers and saves it to a local system. Downloaders automate transfers, support resuming interrupted downloads, and optimize bandwidth usage.

Types include general download managers that handle HTTP, HTTPS, or FTP downloads; torrent clients using peer-to-peer sharing; and specialized downloaders designed for large datasets, software repositories, or unattended operation. Some programs act as browser extensions or are built into web browsers.

Key features commonly found in downloaders include pause and resume, scheduling, multi-source or multi-threaded downloads, bandwidth throttling, and integrity verification through checksums or digital signatures.

Torrent clients implement the BitTorrent protocol, connecting to trackers or using distributed hash tables, exchanging pieces with peers, and assembling the file locally. They rely on seeds and peers and can use magnet links instead of .torrent files.

Security and reliability considerations include the risk of malicious software, corrupted files, or fake download sources. Users should verify file hashes or digital signatures, download from trusted sources, and keep software up to date.

Legal and ethical issues vary by jurisdiction and content. Downloaders are commonly used for legitimate purposes, such as obtaining software distributions, open data, or backups, but may be used to obtain copyrighted material without authorization, which is illegal in many places.

Examples include wget, curl, and aria2 as HTTP/FTP-based tools; qBittorrent and Transmission as widely used torrent clients; and download managers like Internet Download Manager or Free Download Manager.