Frinika is a free, complete music workstation software for Linux, Windows, Mac OSX and other operating systems running Java. It features a sequencer, soft-synths, real-time effects and audio recording.

Frinika is a free, complete music workstation software for Linux, Windows, Mac OSX and other operating systems running Java. It features a sequencer, soft-synths, real-time effects and audio recording.

The LinuxSampler project was founded in 2002 with the goal to produce a free, (cross-platform), streaming capable, open source, pure software audio sampler with high stability, efficiency and very low latency, while providing professional grade features, comparable to both hardware and commercial Windows / Mac software samplers and to introduce new features not yet available by any other sampler in the world.

Visual Front Ends ~ GUI:

QSampler

JSampler
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. There are other, secondary, things it can do, such as improvise on its own. It has also been used for transcription. Because rhythm-section (e.g. piano, bass, drums) accompaniment is automatically generated from chords, Impro-Visor can be used as a play-along device. Now having a wider array of accompaniment styles, its use is not limited to jazz.

www.cs.hmc.edu
sourceforge.net/projects/impro-visor
en.wikipedia.org/wiki/Impro-Visor
Raven Lite is a free cross-platform software program that lets users record, save and visualize sounds as spectrograms and waveforms. Raven Lite is intended for students, educators, and hobbyists and can be used for learning about sounds, as an aid in birdsong recognition, and in musical instruction.
This is a program for stretching audio. It is suitable only for extreme sound stretching of the audio (like 50x) and for applying special effects by “spectral smoothing” the sounds. It can transform any sound / music to a texture. The program is Open-Source and it’s released under the version 2 of the General Public License. You can download the source code for Linux or the Windows binaries.
The Robust Audio Tool (RAT) is an open-source audio conferencing and streaming application that allows users to participate in audio conferences over the internet. These can be between two participants directly, or between a group of participants on a common multicast group.

mediatools.cs.ucl.ac.uk
freshmeat.sourceforge.net/projects/rat
NINJAM is open source (GPL) software to allow people to make real music together via the Internet. Every participant can hear every other participant. Each user can also tweak their personal mix to their liking. NINJAM is cross-platform, with clients available for Mac OS X, Linux and Windows. REAPER (our digital audio workstation software for Windows and OS X) also includes NINJAM support (ReaNINJAM plug-in).

xwax is an open-source Digital Vinyl System (DVS) for Linux. It allows DJs and turntablists to playback digital audio files (MP3, Ogg Vorbis, FLAC, AAC and more), controlled using a normal pair of turntables via time coded vinyls.
It’s designed for both beat mixing and scratch mixing. Needle drops, pitch changes, scratching, spinbacks and rewinds are all supported, and feel just like the audio is pressed onto the vinyl itself.
The focus is on an accurate vinyl feel which is efficient, stable and fast.

MusE is a MIDI/Audio sequencer with recording and editing capabilities written originally by Werner Schweer, and now developed and maintained by the MusE development team. MusE aims to be a complete multi-track virtual studio for Linux. It is published under the GNU General Public License.

EplayOrgan is a multi purpose organ intended to be playable by organists and versatile enough to be useful to everybody with an interest in organs. It will load and be playable almost instantly and does not need an expensive computer with huge amounts of memory.
midimusic.github.io/tech/eplayOrgan

Simple interface. Powerful music management. Smart Playlists. Advanced track tagging. Automatic album art. Lyrics. Streaming Radio. Podcasts. Secondary output device support. Cross-platform. Easily extensible with 50+ plugins available.

ocenaudio is a cross-platform, easy to use, fast and functional audio editor. It is ideal for people who need to edit and analyze audio files without complication. ocenaudio also has powerful features that will satisfy more advanced users including VST plugin support.
