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

A Multitrack tablature editor and player.

The software to compose music, transcribe your favorite songs, or simply read the thousands of tabs available on the Internet.

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...

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

Sibelius is a scorewriter program, created by Sibelius Software (now part of Avid Technology) for Microsoft Windows, OS X, and historically RISC OS.

Impro-Visor (short for “Improvisation Advisor”) is a music notation program designed to help jazz musicians compose and hear solos similar to ones that might be improvised. The objective is to improve understanding of solo construction and tune chord changes.

Band-in-a-Box is an intelligent automatic accompaniment program. You can hear and play along to many song ideas and go from "nothing" to "something" in a very short period of time with Band-in-a-Box as your "on demand" backup band.

GNU LilyPond is a computer program for music engraving. One of LilyPonds major goals is to produce scores that are engraved with traditional layout rules, reflecting the era when scores were engraved by hand.

Aria Maestosa is an open-source (GPL) midi tracker/editor. It lets you compose, edit and play midi files with a few clicks in a user-friendly interface offering keyboard, guitar, drum and controller views.

GNU Denemo is a music notation editor that lets you rapidly enter notation for typesetting via the LilyPond music engraver. You can compose, transcribe, arrange, listen to the music and much more.

EasyABC allows you to edit and play abc files. It supports conversion from MusicXML and MIDI to ABC. The latter uses a custom implementation (midi2abc is not used) in order to produce very readable ABC output. Direct midi input is supported for people with a midi keyboard.