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


  • Sunset
    Jun 25, 2018

    nice vst but so much small for 4k resolution
    need resize system like spire and sylenth1

  • Fantastic Synth 🙂 Very personal sound and high quality presets. Very simple to program thanks to an immediate interface. I hope to find a wavetable oscillator in a future update

  • Maxim S.
    Jul 11, 2018

    Hi Adam, can I install the plug-in on the computer and laptop with one purchase?

    • Adam Szabo
      Jul 11, 2018

      Hi Maxim, yes its no problem as long as they are your computers!

  • Chronic Distortion
    Jul 16, 2018

    Great plugin.
    But I hope in a future update that the loading time will be shortend for now i have to wait 10-15 sec for each viper to be loaded in (FL20). But for the rest it sounds awesome delay is one of the best i ever heard even better the the virus ti in my opinion.

  • Dylan Loera
    Jul 19, 2018

    Dude! Downloaded the Demo since 64bit is finally released … and man oh man, is this the next synth for Trance Music, and EDM in general! Sounds 10x more full, warm, and rich than both Serum and Spire! Now you just need to get ol’ Sunny LAX to make some preset packs for you! 10/10 my friend, 10/10 … Going to buy it for my Birthday in August

    • Adam Szabo
      Jul 19, 2018

      Thanks, Im glad you like it!

    • Pascal Gregory
      Jul 21, 2018

      I got all the factory soundbanks, the free Trance bank and the commercial hardstyle bank so far – that’s around 500 presets. I think, Viper is so easy to program, but I love the idea to would have access to many more soundbanks, maybe in combination with a good preset manager. Viper is a dream machine with 0 % fiddling factor but 100 % joy factor. Adam, you have to promote this thin much much better!

      • Eyezer Music
        Aug 18, 2018

        I am working on Soundbanks for Viper. But I can’t say when I will start releasing them because I have some issues in other parts of life I have to fix first. But at the moment 2 sounds of 125 presets each are planned. Possibly a third sound bank of 100-125 presets as well. I have to do more research before I decide what platform to use to sell them. But it will be worth the wait because I think I did a good job on my presets. I’ve gotten good feedback from some of my other presets for other synths so I hope people will like what I have in store 🙂

        • Pascal Gregory
          Aug 19, 2018

          Sounds awesome, I’ll become definitely a customer. The more soundbanks for Viper available, the better – and this is, because Viper is the only vsti which has the sonic power I need for electronica creations. Rich parts and creative arpeggios with fx are its strengths. So I would be pleased to purchase soundbanks which cover the ambient side, and gates/arpeggios as well.

  • michael
    Jul 21, 2018

    And again a nightmare to Mac os users while there is not an MAC version yet, as a trance pluck dance progressive lover of Adams patches for any other vst why no mac…:(
    Please try to find a way in 2018 the make an OSX version ( from 10.10.5 Yosemite , still one of the best stable vst musci gear running platforn system,to later if possible)
    for Cubase running app 8.5 or 9.5 cant wait to buy the vst VIPER

    hurry up Adam

  • Joe R.
    Jul 27, 2018

    As you can see or hear. From a musician to musicians.
    Best choice. I loved the JP6K so i fell again in love with the viper.
    The sound quality is impressive and well chosen preset patterns.
    Keeps me playing without stopping. For me endless fun.
    My first choice for starting a song.

  • Psychic Overkill
    Jul 29, 2018

    hmm…. maybe Adam is a Mac hater.

    I want to buy Viper and i can’t :'(

    Please hurry Adam because i want to sell my Virus!!

    • Adam Szabo
      Jul 29, 2018

      I do not hate Mac. Currently it is not possible to export to Mac with FlowStone.

      • Psychic Overkill
        Jul 29, 2018

        I was just kidding mate but do you have any idea when this vst is available for Mac?

  • Michael
    Jul 30, 2018

    Yes OSX Please
    From Yosemite 10.10 .5 up
    Note all Max users do not update to

  • Michael
    Jul 30, 2018

    Just Sierra is fine on Mac
    Made A type misstake
    Do not uodate to high Sierra

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