X-Jupitae Flexoid

X-Jupitae Flexoid free software-synthesizer by CK_Modules

X-Jupitae Flexoid is a free software synthesizer developed by CK_Modules. Available format(s): VST for Windows.

X-Jupitae Flexoid is a synthesiser with three different simultaneous oscillators allowing 11 Voices per note with up to 26 Waveforms, all with user defined max Harmonics (1-512).

Main Features:

  • 3 Different Simultaneous Oscillators allowing 11 Voices with up to 26 Waveforms, All with user defined max Harmonics (1-512):
    • Osc A: ‘Morph’ 16 wave stages (multi-mode).
    • Osc B: ‘Multi’ 8 Voice.
    • Osc C: ‘Flexi’ Dual Voice (multi-mode).
  • Dual multi-mode filters – Serial or Parallel.
  • 4x Graphic 32 stage envelopes.
  • Ribbon and XY Pad controllers.
  • Very flexible modulation options.
  • 28 note polyphony, Mono mode.
  • Interactive pattern arpeggiator.
  • Full Multi-FX section:
    • Gate.
    • Compressor.
    • 5 Band Eq.
    • Degrader.
    • Distortion.
    • Ensemble.
    • Auto Panner.
    • Stereo Image.
    • 4v Chorus.
    • 5 Tap Delay/Echo.
    • True Stereo Reverb.
  • Large GUI providing quick and easy access to all Synth functions.
  • Activation Keycode can be found on the CK_Modules&VST Forum page.

NOTE: This Synthesiser is a variation of “X-Jupitae Wide-Boy” and shares the same GUI functional layout. It provides the user with 3 different oscillator types ‘Morph’, ‘Multi’ and ‘Flexi’ which can be used simultaneously to generate a different soundscape with up to 11 voices per note.

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Tunefish 4

Tunefish 4 free software-synthesizer by Brain Control

Tunefish 4 is a free software synthesizer developed by Brain Control. Available format(s): VST, VST3, Audio Unit for Windows 64b, macOS.

Tunefish 4 was developed as a smaller replacement of Tunefish 3 with roughly the same power, it is however not compatible and uses different synthesis algorithms. It was developed for the 64k intro “Turtles all the way down” by demoscene group Brain Control and is available as VST/AU.


  • Improved UI compared to TF3 which will visualize all modulations.
  • Uses an additive synthesis based wavetable generator.
  • The Noise generator can produce any frequency of noise with any bandwidth.
  • Lowpass, Highpass, Bandpass and an improved Notch filter are available.
  • 2 ADSRs and 2 LFOs that can be linked to pretty much any important knob using a modulation matrix.
  • Supported effects are Flanger, Chorus, Distortion, Delay, Reverb, EQ and Formant.
  • The effects stack allows for any permutation of up to 10 effects.


SyndtSphere – Sound Surfer Synthesizer

SyndtSphere - Sound Surfer Synthesizer free software-synthesizer by Klevgränd Produktion

SyndtSphere – Sound Surfer Synthesizer is a free software synthesizer developed by Klevgränd Produktion. Available format(s): VST, Audio Unit for Windows, macOS.

SyndtSphere is basically a sphere version of the polyphonic synthesizer Syndt. It offers a brand new way of finding the optimal sound; by rotating a sphere that consists of more than 70 professionally created states anyone can dial in the perfect sound. In addition to the sphere, a ping-pong delay and a few more global settings are available.

{See video at top of page}



Subtilior4 free software-synthesizer by Grushenko

Subtilior4 is a free software synthesizer developed by Grushenko. Available format(s): VST for Windows.

Subtilior4 is described as “a strange additive synth which can produce simple and magic sounds”.

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Sprike free software-synthesizer by Cognitone

Sprike is a free software synthesizer developed by Cognitone. Available format(s): VST, Audio Unit for Windows, macOS.

Sprike is an extended variant of Tunefish4, the virtual analog synth originally created by Brain Control.

We made Sprike cooperate more nicely in a MIDI-controlled environment (MIDI sequencers). Following MIDI standards, it responds to bank and program selection messages, master volume and pan controllers. Presets are stored in compliance with operating system conventions. We also added four new MOD sources and enhanced it with an on-screen keyboard. The user interface was enhanced with master volume/pan controls and a level meter. Delay times can be set in terms of note lengths.

Sprike is very lightweight, so you can add 10 or more instances to your project without much impact on CPU load. It has the same expressive and crisp sound as Tunefish and comes with a new bank of factory presets.

Sprike is free open source software. You will find its source code on GitHub.



NanoX2 free software-synthesizer by Pluggotic

NanoX2 is a free software synthesizer developed by Pluggotic. Available format(s): VST for Windows.

NanoX2 is an additive sequenced groovebox that features:

  • A raw 8bit-style sound inspired by the sound of gaming systems & consoles from the past.
  • A sequencer that triggers eight partials inspired by NanoSynth (by Oliver Wittchow & Julian Rohrhuber).
  • A scene-morphing sequencer that will fuse the previous features into a nice mess.

Differently from its predecessor, NanoX2 doesn’t require MIDI notes to be triggered and pitched. Open it and just press play on your sequencer to start the serenade, it’s loaded with 124 preset patterns.

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microTERA free software-synthesizer by VirSyn

microTERA is a free software synthesizer developed by VirSyn. Available format(s): VST, Audio Unit for Windows 64b, macOS.

microTERA for Windows and Mac OS X is available free exclusively on the CD cover disc of several magazines – German magazine Keys & Music Tech in the UK.

The iPad version is available to purchase in the App Store.

Features (Mac & Win):

  • Additive Waveshaping Synthesizer (Mixture between VirSyn Cube and VirSyn TERA).
  • 3 Oscillators (Sinus, Tune & Fine-Tune, individual Lever-Potis, Pitch and Level can be modulated).
  • 32 Voices per Instance.
  • Portamento.
  • Spread-Mode.
  • 2 LFOs (Rate, Sync to Part & MIDI & Voice & Key, Waveforms: Sine, Triangle, Square, Ramp up, Ramp down, S&H, Random).
  • 2 Multi segment Envelopes, each Envelope can have 64 segments.
  • On-Screen Keyboard with Modulation wheel and Pitch-Bend (Range up to -/+ 36 Octaves).
  • The heart of the microTERA: the Additive Shaper with Spectrum and Noise Parameter.
  • 3 effects: Distortion, Delay, Modulation.
  • Amp Section: Level and Pan can be modulated, LoFi-FX (Bit reducer and Sampling rate Reducer).
  • 128 Presets.
  • The well known Slotmachine: “intelligent” Randomize Function.

Features (iPad):

  • Waveshaping Synthesizer:
    • Wavehaper with user programmable shape.
    • Spectral shape specification.
    • Three sine oscillators.
    • Feedback input for noise components.
    • 4 Low frequency oscillators.
    • 4 Envelopes with tempo sync.
    • 64 time/level segments per envelope.
    • Monophonic or polyphonic with 16 voices.
    • More than 160 factory presets, unlimited user presets can be shared.
  • FX:
    • Chorus with four delay lines.
    • 8 pole Analog Phaser.
    • Distortion effect with Tube/Tape emulation.
    • Stereo Echo/Delay effect.
    • Hi end reverberation unit.
  • Live:
    • Play melodies live with the onscreen keyboard. Drag fingers for slides and vibrato.
    • Optionally use CoreMIDI* compatible hardware keyboard.
    • Dozens of scales selectable.
    • Variable Keyboard layout for scale optimized playing.
    • Full featured programmable Arpeggiator.
    • Uses programmable sequences with up to 32 steps.
    • Can trigger single notes and chords.
    • Unique randomizer generates Arpeggios with 100% usability.
    • 32 Arpeggios included, unlimited user arpeggios possible.
    • For each step you can program tie, accent, transposition and note order.
  • Global:
    • Audiobus compatible (Input slot).
    • Inter App Audio.
    • Audio pasteboard. Copy audio recordings to Clipboard for use with other Apps (e.g. Intua BeatMaker and many others).
    • Exchange user presets with File Sharing in iTunes.
    • Support for virtual MIDI input connections.
    • Publish loops and recordings online with the SoundCloud audio platform.

Price: $9.99 in the App Store.

{See video at top of page}



Kx-Modulad free software-synthesizer by KX77FREE

Kx-Modulad is a free software synthesizer developed by KX77FREE. Available format(s): VST, VST3 for Windows 64b.

Kx-Modulad is a virtual analog modular synthesizer with a stereo SF2 player and an additive synthesis WaveTracer to build high quality waveforms.

WaveTracer features:

  • Full parameters controls to make Additive Waveforms with no aliasing.
  • Full 32-bit High Quality Waveforms.
  • Easy to use and to create analogue waveforms.
  • Same quality for all clock frequencies: 44.1 kHz to 192 kHz.
  • Independent WaveTracer engine: KxWaveTracer.exe.

Modular Synthesizer:

  • Stereo routing.
  • All modulations are pre-connected, no cables on the GUI.
  • Skin with variable background color.
  • 3 Polyphonic EGs with for each segment: curves, velocity and Kbd controls.
  • 1 Monophonic EG with for each segment: curves, velocity and Kbd controls.
  • Multiple trigger sources and sync for the EGs and the LFOs.
  • 2 Oscillators with 2 waveforms and 2 outputs with Phase modulation and Sync.
  • 2 independent Sub Oscillators.
  • 1 Stereo SF2 player.
  • 2 Monophonic LFOs with 2 Rates and ASR EG.
  • 2 Multimode VCFs.
  • Mixer with 6 sources: Noise, VCO1 1-2, VCO 2 1-2, Ring, VCO1 Width, VCO2 Width and 3 outputs: VCF1, VCF2, VCA.
  • Each mixer voice can be modulated by different sources.
  • Noise Generator with an EQ.
  • Sample&Hold.
  • Ring Modulator.
  • 6 host sync clocks.
  • 2 MIDI inputs.
  • 1 Distortion.
  • 2 Delays with sync, multimode filter and modulation oscillator with sync.
  • 1 Scope with 100 ms of buffer size.
  • Full MIDI learn.
  • Full NRPN implementation.
  • 128 nice KX presets.


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Heliox free software-synthesizer by CO2Sound

Heliox is a free software synthesizer developed by CO2Sound. Available format(s): VST for Windows.

Heliox is a rather simple experimental synthesizer, with a “no-frills” GUI, capable of “weird” textures and noises, as well as “normal” synth sounds, like pads, leads and basses.

Main features are:

  • monophonic, with 30 oscillators bank.
  • adjustable oscillators’ frequencies, ranging from single frequency to harmonic and non-harmonic series.
  • oscillators can be purely sinusoidal, or “shaped” by an adjustable parameter.
  • adjustable attenuation factor between successive oscillators.
  • 30 LFOs, each modulating amplitude of corresponding oscillator.
  • adjustable LFOs’ frequencies, similarly to oscillators.
  • LFOs can be purely sinusoidal (“bell-like”) or “shaped” by 2 adjustable parameters: center and sharpness.
  • phase shift between successive LFOs is adjustable.
  • LFOs can be periodic or randomly intermittent, with adjustable “density”.
  • ADSR envelope.




Harmonaut free software-synthesizer by ToneBytes

Harmonaut is a free software synthesizer developed by ToneBytes. Available format(s): VST for Windows.

Harmonaut is a simple VST instrument that implements an additive synthesis with four waveform types and 32 harmonics that can be simple drawn with the mouse. In the same way can be adjusted the attack, decay, sustain and release for each harmonic. Additional timbre adjustments are made using LP/HP filter, LFO and chorus.

Main features:

  • 32 drawable harmonics with separate ADSR per harmonic.
  • 4 waveform types (sine, saw, triangle and square).
  • Multimode LFO synced with BPM.
  • Internal chorus.
  • Easy control with pop-up menus.
  • 64 factory presets.
  • Built-in preset manager with ability to patch name editing.

In addition, VST automation and full MIDI Learning are supported.

{See video at top of page}

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