Axel does the same thing any other download accelerator does: it opens more than one HTTP/FTP connection per download and each connection transfers its own, separate, part of the file. It may sound weird, but it works very well in practice. For example, some FTP sites limit the speed of each connection, therefore opening more than one connection at a time multiplies the allowable bandwidth. Be forewarned that some FTP operators don't like it when you do this. It is better to open the additional connections on several servers and download from all of them simultaneously. Axel supports this. You may either specify a list of mirrors to use or tell the program to search for mirrors.

The difference between Axel and other (mostly Windows-based) accelerators is that it does not write data to separate files and join them later. Axel puts all the data in the right file, in the right order, at download time. This is possible, because most Unix file systems allow you to write data after the end-of-file. Axel is console-based and uses few system resources.