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


  • Joe R.
    Dec 11, 2018

    The new resizeable 1.04 is great to use. Great Pleasure. Thanks for the labour.

  • Monte Emerson
    Dec 13, 2018

    I’m trying to download the update per the instructions recently mailed out but I’m not having any luck.

    • Adam Szabo
      Dec 13, 2018

      The site might have had problems because of the traffic. Just keep trying multiple times

  • Max
    Dec 15, 2018

    Hi Adam, what are you planning in the next patch?

    • Adam Szabo
      Dec 15, 2018

      It should be a bigger update so it will take time, but one feature will be to load own skins 😉

  • KcX
    Dec 20, 2018

    Any chances “komplete” integration with Komplete Kontrol? I know I can use it by open instrument and manually assign controls, but It would be nice to have it in search results too.

    I know I will repeat what hundreds have said already, but it is GREAT synth!!! Very user friendly! I couldn’t understand how all these oscilators filters, envelopes work until VIPER. GREAT GREAT INTERFACE and even greater SOUND!!!

  • Yukio
    Dec 24, 2018

    Are not you selling Viper?

    • Adam Szabo
      Dec 24, 2018

      I am selling it.

  • Max
    Dec 26, 2018

    Privet Adam ) Is there any information on the next patch, other than the possibility of changing skins ? And is it possible to make a selectable anti-aliasing x8, x16, etc. Sorry for my googlish )

    • Adam Szabo
      Dec 26, 2018

      I have to rewrite the entire GUI for the user skins to work and it will be big work, so I cannot promise anything else at the moment. Oversampling is already built in the synth and optimized.

  • kostas
    Dec 29, 2018

    hello ! you should make i mac version too! your synth sounds Awsome!

  • Westur
    Dec 30, 2018

    Can you make it available for a renting option just like serum?

    • Adam Szabo
      Dec 30, 2018

      Its technically not possible at the moment

  • Sergey
    Dec 30, 2018

    Downloaded demo, tried it in Bitwig Studio 2.4 64bit, Windows 10 64 bit. 64-bit version of Viper produces some unwanted random clicks during playback, and always clicks when I switch between tabs. Is it a known bug?
    32-bit version works seamlessly. I don’t know exactly about the future of 32-bit plugins support in my DAW, so the bugfix is very much expected.

    • Adam Szabo
      Dec 30, 2018

      I haven’t noticed this, I will take a look

      • Sergey
        Dec 30, 2018

        clicks on tab change began to appear after adding automation

        • Adam Szabo
          Dec 30, 2018

          It seems for some reason changing tabs uses too much CPU. For now, either increase your audio buffer, or lower the Viper Gui size to not get clicks and pops, or close the Viper gui.

          • Sergey
            Dec 30, 2018

            32 bit version has no such issue..

            Russian Federation
    • Daniel
      Jan 01, 2019

      I have noticed the clicks when I move the mouse over the Arpegiator view while I play a note. I’m using Viper 1.04 64 Bit and Fl Studio 20.

      • Adam Szabo
        Jan 02, 2019

        Yes the arp is redrawn when the mouse is over it. Hopefully I can find a fix, in the mean time dont move your mouse over the arp while playing, or lower the gui size to stop the clicking.

  • Adriana
    Jan 13, 2019

    Love the synth wish it had drawable wave tables tho

Leave a Reply to Adam Szabo

Your name here
Your name here
Aug 14, 2020

Gravatars are enabled. Register for free!


  • Your cart is empty.

Follow on Facebook