Software drum machines

LMMS (formerly Linux MultiMedia Studio) is a digital audio workstation application program. It allows music to be produced by arranging samples, synthesizing sounds, entering notes via computer keyboard or mouse (or other pointing device) or by playing on a MIDI keyboard, and combining the features of trackers and sequencers. It is free and open source software, written in Qt and released under GPL-2.0-or-later.

Software synthesizer

open source drum machine software