Super Sound - Super Sound is a resourceful audio and music editor.
SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).
Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
FamiStudio - FamiStudio is very simple music editor for the Nintendo Entertainment System or Famicom. It is designed to be easier to use than FamiTracker, but its feature set is also much more limited.
Audio Video Editor and Mixer - Audio Video Editor and Mixer is a tool that helps you add changes to your video and audio files.
MOTU Digital Performer - Get inspired, then refine your mix — all in a singular workflow.