ZynAddSubFX (also now called Zyn-Fusion) is a free and open-source software synthesizer for Linux, Mac OS X and Microsoft Windows. As of version 3, the completely new user interface is being released under proprietary terms with an open-source-eventually intention while the synthesis engine remains under the original GPL terms.^[2]

For sound generation it has three hybrid synth engines that combine additive, subtractive, Fourier and other synthesis methods. No external samples are used to produce the sound; everything is done by synthesis. The synthesizer has effects like reverberation, echo, chorus, distortion, equalization and others, and supports microtonal tunings.^[3][4]

The original author of ZynAddSubFX is Romanian programmer Nasca Octavian Paul.^[5][6] The project was started in March 2002^[3] and the first public version (1.0.0) was released on September 25, 2002.^[7] Since 2009, the new maintainer is Mark McCurry.^[8]

ZynAddSubFX combines several different methods of audio synthesis in order to create sounds: additive synthesis by the ADSynth engine,^[3] subtractive synthesis by the SUBSynth engine,^[3] and an original algorithm used to generate wavetables in the PADSynth engine.^[9]

ZynAddSubFX was featured in the KVR One-Synth-Challenge contest.

In November 2013, Unfa released an album that was entirely made with ZynAddSubFX. Slavonic pagan ambient project Svitlo albums were created using ZynAddSubFX as synthesizer.

• Yoshimi (synthesizer), Linux only, based on ZynAddSubFX 2.4.0
• Free audio software
• Linux audio software