Hydrogen

Hydrogen is a free program to create your own music bases in just a few minutes.

It has a wide-ranging percussion library so you can play all kinds of custom rhythms. You just have to mark the sounds on the timeline. You can create different patterns and repeat them in loop or combine them using the upper side of the program's window, multiplying your options.

There are several quite comprehensive sound libraries included in the program by default, and you can add your own rhythms to create something entirely original.

It also includes a mixer that complements the available customization options. Without a doubt a useful application, and it's completely free.