Viper aims to deliver the sound characteristics of legendary hardware synthesizers in a virtual format. We can call Viper a Virtual Performance synth, with a vast array of features like: multiple oscillator types with user waveforms, Sync, Frequency Modulation, Ring Modulation, unison up to 8 voices, filter saturation, filter routings, mod matrix, high quality effects, a powerful arpeggiator, and much more!

A lot of time and research has been invested to make the sound engine of Viper capable of delivering a wide array of sounds, everything from smooth, lush pads, huge basses, and powerful leads, typically associated with traditional analog synthesizers. This was achieved with careful coding, experimenting, analysing hardware synths, and using the ear to fine tune the controls. A constant randomization is also active in the synth to slightly alter its sound to mimic electronic components.

The engine is written in optimised code to use as little CPU consumption as possible, while maintaining a high quality sound engine, finding a good balance between the two. The synth automatically turns off any parts that are not used to further reduce CPU usage. Viper also has a smoothing algorithm for its controls to remove the ‘steppyness’ when it goes between values to give that extra polished sound.

Key features:
● Classic Oscillators with user waveforms
● Multisaw (up to 9x Sawtooth waveform)
● Sub Oscillator
● Noise with coloring
● Punch
● Osc Sync, FM, RM
● Unison up to 8 voices
● 2 Zero Delay Feedback filters with Low Pass, High Pass, Band Pass, Band Reject (notch)
● Filter Saturation curves
● 4 Filter routings: Serial 4, Serial 6, Parallel, Split
● 4 Envelopes: Filter Env, Amp Env, Mod 3 and Mod 4
● 3 LFOs with Oscillator shape morphing
● Mod Matrix
● FX:
● Character (analog boost)
● Distortion
● Filter effects: Ring Modulator, Frequency Shifter, Vowel Filter, Comb Filter
● Phaser
● Chorus
● Delay
● Reverb
● Equalizer
● Arpeggiator with user patterns and Midi Out
● Built in Preset browser
● Section locking
● Midi learn
● Resizable GUI


Download demo version:
Demo restrictions: Preset saving is disabled, silence every 60 seconds. (Because of the demo limitations, automation is not available in some hosts, but is fully functional in the retail version)
Requirements: Win 32/64 compatible system with SSE2 (or higher).

User Manual:
The user manual for Viper can be downloaded from here: Viper Manual.pdf

This is a 32 & 64-bit VST for Windows only! All future updates are free!
Please evaluate the demo thoroughly before purchasing!

Why no Mac version?
Unfortunately, FlowStone does not yet support export to AU, Mac VST yet. As soon as FlowStone supports this, the synth will be available in this format.

Free Soundbanks:
Daniel Craighead Trance Access for Viper Vol.1.zip


  • Sean
    Mar 11, 2019

    It would be amazing to get the filters and fx section as a seperate fx plugin.

  • IAN
    Apr 07, 2019


    • Adam Szabo
      Apr 07, 2019

      No news, as its not possible to create a Mac version with FlowStone

  • Stefan
    Apr 09, 2019

    Is there an upcoming easter sale?
    Want to know before I purchase. 🙂

    • Adam Szabo
      Apr 09, 2019

      There will be sales after the summer when I have built a new website, there are issues with it right now

  • DJ Perryboy
    Apr 12, 2019

    Is factory presets 100% royalty free?

    • Adam Szabo
      Apr 13, 2019

      Yes, you can use them in your own productions

  • G
    May 16, 2019

    How many licenses are available when you buy it?

    • Adam Szabo
      May 16, 2019

      You get one license which is only for you, but you can use it on your computers

  • Theko
    May 21, 2019

    very happy to be a new Viper user!!

  • Sergey
    Jun 15, 2019

    Adam, can you create this amazing synth in NI Reaktor ensemble version???
    I’m waiting for OSX version for so long …

    • Adam Szabo
      Jun 16, 2019

      Unfortunately I am not familiar with Reaktor

  • Theko
    Jun 21, 2019

    Waiting for Viper Factory 4 soundbank!

  • Štefan
    Jun 27, 2019

    Yes factory soundbank 4 would be great 🙂

  • Simon Weber
    Jul 01, 2019

    Great Plugin you made, Adam! Very enjoying this machine! Thanks for it! 🤘

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