composing

FamiTracker is a free windows tracker for producing music for the NES/Famicom-systems. The interface is based on MadTracker and should be easy to use if you've been using trackers before.

Compose, arrange, and share music using free, open-source software for Windows, Mac, and Linux with integrated playback, fast note entry, MIDI, MusicXML, PDF support, multilingual UI, and direct connection to an online sheet music community for sharing scores.

Schism Tracker is a free reimplementation of Impulse Tracker, a program used to create high quality music without the requirements of specialized, expensive equipment, and with a unique "finger feel" that is difficult to replicate in part.

Rosegarden is a well-rounded audio and MIDI sequencer, score editor, and general-purpose music composition and editing environment.

NanoStudio is a recording studio for iOS, OS X and Windows. It has virtual analogue synths, sample trigger pads, a comprehensive sequencer, a sample editor, a mixer and multiple effects all integrated into a single application.