Aria2 is a lightweight command-line download utility that fetches files over HTTP, FTP, SFTP, BitTorrent, and Metalink by splitting transfers across multiple sources, with a remote interface for automating queues.
Aria2 is a command-line download utility that does one job and does it invisibly, fetching files from multiple sources at once without a window in sight. You hand it a URL, a torrent, a magnet link, or a list of mirrors, and it opens several connections per file, switching between sources when one slows down. Because it has no interface of its own, it is normally driven by scripts, a web dashboard, or another application that needs a download engine. A built-in remote interface exposes the whole queue over HTTP, so tools can add downloads, read progress, and pause work programmatically. Its value is reliability on long transfers.
Running it well is about configuration rather than clicking. Options live in a text file or on the command line, covering how many connections to open per server, how much of the line to use, where a session should be saved, and which shell command to run when a download finishes. That makes it a natural fit for servers: start the process, save the session, and it will still be there after a reboot. Many graphical clients are really just dashboards for it, and desktop users who prefer buttons and account management may find a full application such as JDownloader 2 easier for everyday downloads, while the engine stays the better choice for automation.
The reason people reach for it over a graphical downloader is efficiency. It pours the available bandwidth into a transfer by using more connections than a browser ever would, and it does so with a footprint small enough to leave running on a cheap server or a router-class device. Resuming is handled properly: an interrupted file continues from the last completed piece rather than starting over, and checksum or Metalink verification confirms the result is intact. Around that core sit the details that make automation practical, including session files that survive a restart, speed limits that keep the connection usable for other work, and hooks that trigger your own scripts when a job completes. Batch work, where hundreds of links are queued from a text file, is where the difference becomes obvious.
Key capabilities and highlights.
A single file can be pulled from several mirrors over multiple connections at once, so the utility saturates whatever bandwidth the line actually offers instead of being capped by one slow server, which makes a visible difference on large disk images, archives, and video files.
HTTP, HTTPS, FTP, SFTP, BitTorrent, and Metalink are all handled by the same command, so scripts and scheduled jobs only deal with one tool whether the source turns out to be a web server, a secure FTP host, or a swarm of peers.
A built-in remote interface lets other software drive the downloader over HTTP or WebSocket, which is how graphical clients, browser extensions, and home-server dashboards manage queues without parsing terminal output, and how they read live speed and progress data.
DHT, peer exchange, magnet links, web seeding, UDP trackers, local peer discovery, selective file downloads, and connection encryption are all included, so there is rarely a reason to install a separate torrent client just to grab a single release.
Interrupted transfers continue from the last completed piece rather than starting again, and checksum or Metalink verification confirms the finished file is intact, which matters when a job runs overnight on a flaky connection or pulls from several mirrors of the same file.
Global and per-download speed limits, a configurable number of connections per server, and a disk cache that buffers writes all help you keep a queue running without hammering either the network link or the storage device underneath it.
It runs as a background service with session save and restore, so a server can keep a queue alive across reboots and hand finished work to your own commands through completion hooks, a pattern that suits automated pipelines and unattended machines.
A plain text list of URLs, a Metalink document, or a torrent file can be supplied as one job, and the session file records everything still pending, which makes repeatable batch downloading straightforward to script and schedule without manual intervention.
Browse historical releases and previous builds.
Common questions about Aria2.
It is a command-line tool, so there is a learning curve, but typical use is a single command with a URL after it. Most people never touch the terminal directly: graphical frontends, browser extensions, and packaged apps wrap the engine, and configuration files let you set sensible defaults once rather than repeating options.
HTTP and HTTPS, FTP, SFTP, BitTorrent, and Metalink. That covers ordinary web downloads, remote servers reached over secure FTP, peer-to-peer transfers, and Metalink files that describe a download across several mirrors with checksums attached.
Yes. Aria2 includes a complete BitTorrent implementation with DHT, peer exchange, UDP trackers, local peer discovery, magnet URI support, and selective downloading of individual files inside a torrent, so it can replace a standalone torrent client for most everyday jobs.
Through the built-in RPC layer, which speaks JSON-RPC over HTTP and WebSocket as well as XML-RPC. Client libraries exist for several languages, and they are what allow a web dashboard or a custom script to add links, query progress, pause jobs, and change speed limits while the process keeps running.
Yes. It starts as a daemon and can save its session on exit and reload it on start, so a server keeps its queue intact across reboots. Combined with completion hooks that fire your own commands, that makes it a practical building block for unattended downloads.
It does when information is available. Metalink documents carry checksums for each file, and a checksum option can be supplied manually for ordinary URLs. Aria2 then compares the hash after the transfer, so a corrupted download is flagged rather than quietly kept. Aria2 also reports mismatches into the session log.
It is an engine rather than a finished desktop application, which is exactly why so many applications embed it. Choose it when you want automation, scripting, and low resource use on a server. Choose a full graphical client when you want account management, a link grabber, and extraction handled through a normal window.
Yes. Aria2 is free software released under the GNU General Public License, with source code available for anyone to inspect, build, or modify. There is no paid tier, no advertising, and no account requirement, and binaries are published for the common desktop platforms.
Aria2 is a lightweight command-line download utility that fetches files over HTTP, FTP, SFTP, BitTorrent, and Metalink by splitting transfers across multiple sources, with a remote interface for automating queues.
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