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The top 10 free synth plugins you should try in 2021

The top 10 free synth plugins you should try in 2021

By Nate [KVR] on

The old adage 'the best things in life are free' rings true for this list of 10 awesome VST synths covering everything from faithful recreations of vintage analog and digital keyboards, to cutting edge wavetable synths and modular synthesis platforms. Check it out!

Free / $25 / $80 / (or $5 / month subscription)


Vital is a spectral warping wavetable synthesizer.

Discover how warping the harmonic makeup of a wavetable can completely create a new set of sounds. Stretch, shift, smear and skew harmonics up, down and around the spectrum to explore new timbres and create sounds you didn't think possible with wavetables.

See how everything works while you play in this visual synth. Vital has animated graphical displays when you need them. Everything moves in real-time so you can see what's going on behind the scenes.

Quickly design sounds with an optimized drag-and-drop modulation workflow. The modulation preview gives you an idea of what things will sound like before you drop the connection. With this, you can try modulating different destinations by dragging around the screen.

Discover new design techniques using Vital's unique features like stereo-modulation. Stereo split an LFO to have the left channel's modulation delayed from the right or give slight stereo time differences to an envelope to create wider stereo effects.

Surge Classic Skin

Surge is a virtual synthesizer released into open source by creator Claes Johanson in September 2018, and maintained by a group of volunteers since then.

It features many synthesis techniques, a great selection of filters, a flexible modulation engine, a smorgasbord of effects, and modern features like MPE and microtuning.

Surge is a wonderful tool. We love it. We think you will, too!

Voltage Modular is designed to be powerful, flexible, and an easy to use virtual modular synthesizer. Voltage Modular Nucleus is an introductory bundle for those that want basic modules and presets. Voltage Modular is cross-platform for OS X and Windows, and supports AU, VST2, VST3, and Pro Tools AAX formats, as well as standalone operation. All plug-in formats can be used as both virtual instrument and effects plug-ins. User patches and cabinet files are freely cross-platform exchangeable.

Voltage Modular was designed from the ground up to address the shortcomings of other virtual modular synth instruments. Featuring six-way pop-up mults on all inputs and outputs, easy repositioning of modules or groups of modules, cables that can be moved and rerouted at all times, and control panels designed to be easy-to-read and operate with extensive visual feedback, including cable signal flow indicators, Voltage Modular offers a clean, polished, virtual modular interface like no other.

All audio processing in Voltage Modular uses high-quality 64-bit double precision math and all module processes are zero-latency and operate on individual samples for true modular performance. This translates to fantastic sounding audio-rate frequency and amplitude modulation, oscillator sync, insane delay feedback, and more.

The innovative module browser allows users to purchase and automatically install modules and sound presets directly from within Voltage Modular for immediate expandability. The number of modules and cabinets contained in a patch is limited only by computer CPU performance.

Synth (Analogue / Subtractive) by u-he

Tyrell Nexus 6

The Tyrell Nexus 6 plug-in was programmed by Urs Heckmann (the mastermind behind u-he) for Amazona.de. This is a virtual analog software synthesizer: the sound engine is circuit-modeled and is similar to the u-he ACE. The features are those that we may expect from a vintage synthesizer like the Juno series from Roland.


  • 2 Oscillators.
  • 1 Sub-Oscillator.
  • 1 Noise Generator.
  • 1 Ring modulator.
  • 1 Signal feedback.
  • 2 LFOs.
  • 2 ADSR envelopes.
  • 1 Modulation Matrix.

VCV Rack is the engine powering VCV modules. Add modules, connect cables, edit parameters, and save/load patches. Create generative patches with your mouse, perform with your MIDI keyboard controller, or connect it to your favorite DAW using the VCV Bridge VST/AU plugin (Coming soon).

In Rack, control voltages and audio signals are equivalent, so you can modulate parameters with sonic-range VCOs to create customizable FM synths or chaotic wave-shaping oscillators. If you already own a modular synthesizer, you can enhance your setup with an audio interface or a CV-MIDI-CV interface module with Rack's CV Interface.


Dexed is a multi platform, multi format plugin synth that is closely modeled on the Yamaha DX7. Under the hood it uses music-synthesizer-for-android for the synth engine.

The goal of this project is to be a tool/companion for the original DX7.


  • Multi platform (OS X, Windows or Linux) and multi format (VST, AU, LV2).
  • The sound engine music-synthesizer-for-android is closely modeled on the original DX7 characteristics.
  • 144 DAW automatable DX7 parameters available from one single panel.
  • Fully supports DX7 input and output Sysex messages; including controller change. This means that you can use this with a native DX7/TX7 as a patch editor and SysEx manager.
  • Each operator have a realtime VU meter to know which one is active.
  • Can load/save any DX7/TX7 SysEx programs. It is also possible to save a single program into a different SysEx file.
Free (suggested donation: £10-20)


pg-8x is a VST instrument plug-in, inspired by the JX-8P. The GUI is modelled after the pg-800, which is the external editor for the JX-8P. pg-8x is patch-compatible to the hardware, which means that JX-8P SysEx files are accepted.


  • 6-12 voice polyphony.
  • Two DCOs with Saw, Square, Pulse, Noise.
  • Hard Sync and Ring Modulation.
  • Two exponential envelop generators.
  • 24 dB resonant LP filter.
  • HP filter (3 stages).
  • Stereo Chorus.

Surrealistic MG-1 Plus Synthesizer

The fun and funky Surrealistic MG-1 Plus Synthesizer is a super authentic recreation of the Realistic MG-1 synthesizer sold in Radio Shack stores in the 80's. The Surrealistic MG-1 Plus delivers fat analog tone in spades, along with a unique polyphonic oscillator section, "bell tone" ring modulation, glide, auto repeat note triggering, oscillator sync, and a number of improvements that tremendously expand its capabilities. Best of all, it's absolutely free.

Surrealistic MG-1 Plus Features:

  • Ultra-accurate analog modeling.
  • Dual oscillator monophonic plus polyphonic oscillator bank.
  • Super fat 24db "ladder" filter.
  • Over 130 presets.
  • "Bell tone" ring modulation.
  • Tempo syncable LFO.
  • Expanded octave ranges.
  • Multiple note priority modes including legato and retrigger.
  • All controls MIDI assignable.
  • Full DAW automation of all controls.
  • Surrealistic MG-1 Plus is available in AU, VST, VST3, AAX, and standalone formats.


The Fury-800 is a software plug-in simulating the classic KORG Poly-800 from 1983. It is written in native C++ code for high performance and low CPU consumption.


  • Two band-limited DCOs with individual envelope generators.
  • Two waveforms with additive harmonics (16', 8', 4', 2').
  • Single (paraphonic) lowpass VCF and Noise.
  • On-board sequencer and Chord Memory.
  • Pseudo-stereo Chorus effect.
  • Up to 64 voices polyphony with Velocity.
  • "God Mode" for real polyphony.
  • Continuous parameter values and direct access.


For those bored of the same old synth sounds, Newfangled Audio Pendulate offers something truly new. Most synthesizers sound similar because they're based on the same technologies. Pendulate is a chaotic monosynth that uses a brand-new oscillator technique to create previously unheard sounds – biting basses, searing leads, and gritty textures. Pendulate, distributed by Eventide, is available for immediate download free of charge.

Pendulate is based on the physics of a double pendulum. What initially looks like randomness contains underlying patterns, interconnectedness, constant feedback loops, repetition, self-similarity, fractals, and self-organization. When designing the Pendulate oscillator, great care was taken to bring out these underlying patterns. The result is an oscillator that can smoothly fade from a sine wave to total chaos, with an expanse of territory to explore in between.

Pendulate's chaotic oscillator is matched with a wavefolder and low pass gate inspired by the ideas of legendary synthesizer designer Don Buchla. These three modules – oscillator, wavefolder, and gate – combine to make previously inconceivable sounds.

Every parameter in Pendulate's three modules can be modulated by an included Envelope Generator or LFO, or by MIDI and MPE sources. The innovative modulation interface allows users to easily and quickly patch any combination of sources to any destination, creating sounds that compel the listener to move with them.

Pendulate's wavefolder is based on a pioneering design from the Buchla 259 Complex Waveform Generator, adding MIX and CUTOFF functions. The low pass gate in Pendulate is based on the Buchla 292's gate, adding controls for POLES and RESONANCE. Pendulate's Envelope Generator and LFO each have multiple outputs generated simultaneously, like a modular synth should. Every modulation output can be applied to every control in the monosynth, resulting in up to 221 modulation points, viewed and controlled in an intuitive single pane. The Double Pendulum, Wavefolder, and Low Pass Gate modules each have animations to show how each module responds to input, and to modulation. Along with three unique color schemes to customize the synth's appearance, 136 Presets provide a launch point for creating experimentation – including artist presets from Matt Lange (Producer, DJ) and Matthew Wang (Composer Film/TV).

Every parameter in Pendulate's three modules can be modulated by an included Envelope Generator, LFO, or MIDI and MPE sources. The innovative modulation interface allows you to easily and quickly patch any combination of sources to any destination—creating sounds that are sure to make you move with them.


  • Wavefolder based on the one in the Buchla 259 Complex Waveform Generator, adding MIX and CUTOFF.
  • Low Pass Gate based on the Buchla 292 adds controls for POLES and RESONANCE.
  • Innovative modulation UI allows modulation over every control from the main page, allowing up to 169 simultaneous modulation routings.
  • MPE support allows amazing control from innovative new controllers.
  • Envelope and LFO each have multiple outputs generated at once, like a modular synth should.
  • Modulation! Every mod output to every control means up to 221 modulation points in an intuitive single pane.
  • Animations! The Double Pendulum, Wavefolder, and Low Pass Gate modules each have animations to show how each module responds to your input, and to modulation.
  • Three unique color schemes to customize your look.
  • 136 Presets including artist presets from Matt Lange (Producer, DJ) and Matthew Wang (Composer Film/TV).

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Discussion: Active
23 June 2021 at 11:43am

This one is missing in the list:

Fathom Mono

26 June 2021 at 7:40am

Fathom has nice specs but its gui and concept are far from finished.Its not a standard gui, the user will spend too many time creating a preset on this synth.

22 July 2021 at 6:33pm

I actually dislike fathom, it doesn't feel complete it sounds pretty good but using it feels a bit rough.

26 June 2021 at 7:30am

Tyrell N6 and Surrealistic MG-1 Plus shouldn't be on this list.

Tyrell N6 it's not a powerful synth and has bugs, it hasn't been updated for many years! Surrealistic MG-1 Plus
its very limited and produce a small number of useful sounds. These two synths aren't top synths.

I understand that Nate is in love with Full Bucket Music, but we need more variety and synths from other sources.

So, as a longtime free plugins user, here is my top 10 list of free synths:

1. Vital - dont come with many content but its the most powerful free wavetable synth available
2. Surge (with the new skin Surge Dark or Royal Surge) - lots of presets, wavetables and fx included!
3. Voltage Modular Nucleus - the (now) free modular synthesizer. has lots of modules and sounds analog. just get it!
4. Toybox Free Pack/User Blocks/Nano CE for NI Komplete Start - modular modules that are better than Reaktor Blocks
5. TRK 01 Bass from NI Komplete Start - this little thing is a beast and can create any type of bass!
6. Dexed - very powerful FM synth, can even load DX7 presets. dont forget to spin the algorithm knob
7. Odin 2 - not so popular, but powerful and fun. its kinda modular, like Thor from Reason
8. OB-XD - classic emulation of Oberheim X. capable of lush analog synth sounds comparable to Prophet 5
9. Mono/Fury - classic emulation of Korg Mono/Poly. very useful for synthwave productions
10. PG-8X - an excellent emulation of Roland JX-8P. it lacks a better browser, a default preset folder and more

7 July 2021 at 8:58am

Your list also includes a full bucket music synth...;).

TRK 01 and the Toybox stuff are both great additions. OB-XD I didn't include because it is technically only free for non-commercial use and need to be purchased if you intended to release any music using that.

Personally I've never experienced bugs with Tyrell N6, and I don't think either that or nor Surrealistic MG-1 being limited in design is necessarily a bad thing. Sometimes simple is better. Each to his own though :).

13 July 2021 at 10:00pm

OB-XD was always free, here on KVR by 2Dat. If discoDSP is going to try to sue people who release music with 2Dat's open source synth, I will make sell as many albums as possibly exclusively using it;).

22 July 2021 at 6:32pm

Voltage Modular is lesser when compared to VCV Rack to me, VCV Rack just has more free stuff of a fairly high quality. Tyrell N6 is a great synth and i don't think many people ever have bugs with using it, something doesn't need to be powerful to be good if you can do something simple well that should be good enough quite frankly.

22 July 2021 at 11:16pm

"simple and good enough" are not characteristics of top 10 synths. We're talking about the best synths, not the reasonable ones. Tyrell N6 have bugs but hardly anyone uses it, so you won't hear complaints. VCV rack is better but the best modules are paid.

28 June 2021 at 7:42am

what a great list.

11 August 2021 at 1:34am

Why Fury800 and not Mono/Fury? For my money (yes, I did make a donation) Mono/Fury is a much better synth. I have owned both the originals, too, and Mono/Poly - Mono/Fury are better sounding, more versatile synths.

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