Downloading Files Faster With Aria2

I found this nifty wget-like tool named aria2. wget can only download a file with a single connection. aria2 is capable of chunking the target file and downloading each chunk with a separate connection.

Depending on the server and speed limits per connection, this can increase the throughput greatly.

Why Are Multiple Connections Faster

The internet is a network of devices. With a single connection, data is traveling through a single pathway (not completely true) and can be bottle-necked along this journey. Multiple simultaneous connections open up for more pathways.

More accurately, there are usually middle-men (web hosting providers) that limit bandwidth per connection and this is a means to circumvent that. In a true and ideal internet, a single connection would be sending small packets through many different paths of the network (by design of the internet), allowing for maximizing throughput.

Note that there will not be a speed up if bandwidth is limited on either the downloader or source server.

How-To

aria2c --max-connection-per-server 16 --split 16 https://example.com/big-ass-file

This splits the file into 16 connections.

Resuming Partial Download

With wget --continue, you can continue a partially downloaded file. This is implicit behaviour with aria2 (sane defaults!).

While downloading with aria2, you’ll notice there are two files:

• the target file. This is really just a placeholder to reserve space. It gets swapped with final file when download is complete.
• a temporary that contains the partial data and metadata for resuming. This file is cleaned up automatically when download is complete.