Aria2 - The Fast and Reliable Download Utility

[Japanese]
Get aria2 - CLI Metalink/BitTorrent client at SourceForge.net. Fast, secure and Free Open Source software downloads
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Introduction

aria2 is a multi-protocol & multi-source, cross platform download utility. The supported protocols are HTTP(S), FTP, BitTorrent (DHT, PEX, MSE/PE), and Metalink.

aria2 can download a file from multiple sources/protocols and tries to utilize your maximum download bandwidth. It supports downloading a file from HTTP(S)/FTP and BitTorrent at the same time, while the data downloaded from HTTP(S)/FTP is uploaded to the BitTorrent swarm. Using Metalink's chunk checksums, aria2 automatically validates chunks of data while downloading a file like BitTorrent.

There are other alternative applications. But aria2 has 2 distinctive features: (1) aria2 can download a file from several URIs(HTTP(S)/FTP/BitTorrent) and (2) If you give aria2 a list of URIs, aria2 downloads them concurrently. You don't have to wait for the current download queue to finish one file at a time anymore. aria2 tries to utilize your maximum download bandwidth and downloads files quickly.

There are also some applications that have the ability of segmented downloading. Typically these applications split a file by the number of threads and download them parallel and wait for all threads to finish. In other words, they don't split unfinished segments adaptively. Normally(if things goes well) there is no problem for this strategy, but if one thread is very slow(i.e. one of the server is very slow), then you have to wait for it to finish.
aria2 can cope with this peculiar situation. aria2 can split segment adaptively all the way down to 1MiB. So you don't have to worry about the above problem. But you might complain: if a slow server is downloading last 1MiB, then you have to wait for that none the less. The nswer is "no". Even in such case, aria2 does the job quite well: aria2 cancels slow server and use the faster server to finish download. In other words, aria2 is very clever and reliable in many situations.

Unlike original Aria, which has GTK+ interface, aria2 provides command-line interface only. But it brings lower resource requirement. The physical memory usage is typically 3MB(normal HTTP/FTP downloads) to 6MB(BitTorrent downloads). CPU usage in BitTorrent with download speed of 1500KB/sec is around 6%.

It is being actively developed by Tatsuhiro Tsujikawa.
Feature requests and comments are all welcome. Please refer to Contact page.

Usage example, FAQs and other useful information can be found at aria2 wiki.

Please visit the project page at sourceforge.net.


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