Rosegarden!

LMMS is a free cross-platform alternative to commercial programs like FL Studio , which allow you to produce music with your computer. This includes the creation of melodies and beats, the synthesis and mixing of sounds, and arranging of samples. You can have fun with your MIDI-keyboard and much more; all in a user-friendly and modern interface.

Ardour is a hard disk recorder and digital audio workstation application. It runs on GNU/Linux, Mac OS X, and Windows. Ardour's intention is to provide digital audio workstation software suitable for professional use.

MuseScore is a free music notation and composition software available for Linux, Windows and Mac.

REAPER is a complete digital audio production application for Windows and OS X, offering a full multitrack audio and MIDI recording, editing, processing, mixing and mastering toolset.

Live is software for creating musical ideas, turning them into finished songs, and even taking them onto the stage.

With TuxGuitar, you will be able to compose music using the following features

Cubase is a computer program for music production/recording.The program offers recording, producing and mixing of sounds in order to make music production for distribution on CDs or the internet.

Caustic is a music creation tool inspired by rack-mount synthesizers / samplers rigs. Everything is real-time and optimized for mobile devices.

OpenMPT (short hand for Open ModPlug Tracker) is a popular tracker software for Windows. OpenMPT is completely free and allows you to create and play back some great music on your computer. Based on the original ModPlug Tracker written by Olivier Lapicque, OpenMPT is free software and supports a wide variety of module formats and offers an intuitive, native GUI as well as advanced features such as VST plugins and ASIO output.

Guitar Pro is first and foremost a program designed to edit tablatures for guitar, bass, and other fretted instruments from 4 to 8 strings.

Qtractor is an Audio/MIDI multi-track sequencer application written in C++ with the Qt framework. Target platform is Linux, where the Jack Audio Connection Kit (JACK) for audio, and the Advanced Linux Sound Architecture (ALSA) for MIDI, are the main infrastructures to evolve as a fairly-featured Linux desktop audio workstation GUI, specially dedicated to the personal home-studio.

Sibelius is the world’s best-selling music notation software, trusted by top composers, publishers, and students alike. With Sibelius 7.5, you can express, accelerate, and promote your creativity in more ways than ever before, enabling you to deliver beautiful, professional scores faster and share audio and video versions of your work—with stunningly realistic musical phrasing—to make your talent stand out from the crowd. It’s the fastest, smartest, easiest way to write music for live performance, film and television, media entertainment, or in the classroom. »

Tracktion is an advanced DAW (Digital Audio Workstation) that uses an intuitive, single-screen interface to ease the music production workflow.