Great free synths – VSTs for Mac

You wouldn’t steal a car… you wouldn’t download a synth? But you can! And they’re free and legal

  • Free musical instruments? No catch, no spam
  • These are the ones I use myself regularly
  • Plus a few I can’t because they’re PC-only, but still cool

Got a fierce case of GAS? I sympathise, I’ve suffered it for years – my Gearslutz ‘owned’ list is either epic or depressing, depending on your perspective. These days, though, it’s really hard to justify going all out to get every synth you findin a secondhand shop or carboot sale, because virtual copies aren’t just available – they’re good.

Crazy thing is, too, a lot of them are free or donationware. Some are glitchy or need a bit of work, but the majority are as good as any commercial, expensive package.

Not everything I use is free, obviously, and I’m comparing my experience of these free VSTs with the likes of Arturia V-Collection and Roland Cloud. The latter in particular is a real resource hog, the trade off for circuit-accurate recreations of classics like the D-50 and modern synths too; there’s a virtual System 8 in the package.

This will grow to be a long list – fortunately for us, there’s a lot of really cool stuff to get started making music without spending money, as long as you have a computer.

  1. Full Bucket Music – analogue Korgs and original concepts too
  2. u-He’s baby Zebra, some cheese and the legendary Tyrell
  3. Open-source Oberheim from discoDSP
  4. Quirky bass synth revived by Martinic
  5. A polyphonic analogue classic, the JX-8P – PG-8X by Martin Lüders
  6. Going Native – a Komplete Start
  7. Overflowing with potential – Surge

My main DAW is a Mac, hence the bias here – but there are some options for Windows users too, and as it happens all of the VSTs below offer Windows versions.

If you don’t have a VST host, there are some recommendations at the end of the article.

Classic synthesizers, name your price – Full Bucket Music

Top of the list for free VSTs has to be the epic work by Full Bucket Music. Musician and programmer Björn Arlt dealt with the lust for unaffordable classic synths by creating virtual versions and has released an astounding number of them as donationware.

These aren’t one-off summer projects that sound awesome and have been abandoned, either – regularly updated with professionally-programmed soundbanks, they’re the sort of thing that makes you wonder how big firms can get it so wrong or neglect their plugins for ages.

Headliners here are the Korg PS synths, replicated in FB-3300, 3200 and 3100. Yes, that’s a ‘free’ download of a 48-voice analogue monster that would cost tens of thousands to acquire, let alone maintain – if you could find one in the first place. Joining them are some classic Korgs – the Mono/Poly, Trident, Sigma and Delta, and a few original creations.

The most recent addition to the family is the quirky ’80s Korg Poly800, in the form of Fury800. It’s expanded and opens up the rather arcane programming in a way that people who stuck to patches on their 800s (like, er, me) will find enlightening.

Itching to see what’s on offer? Go and visit the source: Here are all the Fullbucket VSTs (Windows and Mac, with AU versions too) you can download. For space reasons, I’m not featuring them all here…


  • Impressive analogue emulation, 48 voices, 3 oscillators per voice
  • Can be resized easily, low CPU overhead
  • MIDI learn for controllers
Full Bucket Music's amazing FB-3300 VST - a freeware Korg PS-3300

FB-3300 is a real gift for fans of classic 1970s and early ’80s synthesizer music. The original was a beast, with effectively three PS-3100s in one box, a dedicated 48-key keyboard and a total of 144 oscillators*. Not only that, each key has its own VCA, VCF and envelope generators.

This is a truly big synthesizer with great analogue character – you can only imagine what it was like playing one on stage or studio in the 1970s. If you’re a fan of Tangerine Dream, ELP, Yes or any of the psychedelic/prog artists that made synthesizers cool (or not), you’ll love it.

I can’t vouch for the accuracy of the emulation, but it sounds deeply impressive, is stable and has a scalable GUI so you can actually see the hundreds of parameters you can control. Learning to program the FB-3300 is a daunting task – it comes with a set of presets, thankfully, so you’re ahead of those first electronic musicians…

For all intents and purposes, the FB-3100 is one-third of the PS-3300 sound engine, with a single VCO voice structure but full keyboard polyphony. It’s somewhat easier to program.

Full Bucket Music FB-3100 - a Korg PS-3100 VST for free

The FB-3200 is a little different, as it uses two oscillators with a more conventional mixing approach, it was also equipped with patch-panel recall – a truly innovative feature.

The Full Bucket Music FB-3200 Korg PS-3200 emulation

*sort of. There’s one oscillator per note in an octave; the remaining octaves use the ‘divide-down’ technique common in organs of the era, so an FB-3100 has two voice cards to provide 12 root notes, an FB-3300 has six cards to provide 3 x oscillators/waveforms over 12 notes, etc.

Mono/Fury – a free Mono/Poly?

Of Full Bucket Music’s VSTs, Mono/Fury is perhaps the most remarkable as Korg themselves produce a softsynth MonoPoly for Mac/PC and iOS (iMonoPoly). As Behringer have shown, though, you can’t keep things from being duplicated forever; and Mono/Fury is different to the Korg one.

Full Bucket Music Mono/Fury - a free Korg Mono/Poly VST

The user interface is much simpler and closer to the real hardware in some ways – because Korg’s added a lot of graphics for the preset browser and some effects built in, as well as the software keyboard. Navigating Mono/Fury is therefore a bit easier. The free version doesn’t claim to be 100% accurate, either, but it’s very very close.

Which means it sounds speaker-blowingly, old-school brutal for some patches. It might not have the analogue-recreated accuracy of imperfection, but it’s the spirit of the original through and through. A must-have for any musician.

I don’t have space for all of Full Bucket’s Synths here – but at different times have tried all of them. They’re donation-ware you’ll want to pay for – but don’t have to…

u-He – Baby zebras and cheese

u-He (Urs Heckmann) is well known for two astonishingly powerful softsynths, Zebra and Diva. Zebra is like modular on steroids, or if you want to move away from the capes and patchcords, object-oriented synthesis. Take the best bits of modern synthesizers, pick and choose, and build to your heart – and your CPU’s – content. Diva’s more grounded, but a storming software virtual analogue dream that if it were hardware, would be everywhere.

These flagships cost though. Not an unreasonable amount (they’re actually pretty good value, and you can trade in your old synth for a discount ;) ), but enough to make you think ‘do you need it’. So sensibly, u-He have a few freebies to show what they do…


Described as a baby Zebra, the Zebralette is a single-oscillator version with less flexibility, but still 16-voice polyphonic with ADSR and MSEG envelope generators, wave-morphing and spectral filters that go beyond low or high pass.

Basically that means it sounds WAY better than just a single oscillator synth. There are three effects thrown in too. It’s brilliant, frequently updated, has the vital scalable UI for big monitors and sounds epic.

Zebralette is a single-oscillator version of Zebra - it's free

I tend to dive into solos with this one, depending on the preset, but have yet to get into programming it; again, if you’re doing the thing of looking for more sounds in the hope of stumbling over something that expresses what you want, do not overlook it!

Triple Cheese

Breaking from the usual model of synthesis, Triple Cheese uses comb filters, with an initial noise generated from simple models, then manipulated or stacked. Recognisable shaping from envelopes and LFO is on offer, before some effects for chorus, delay and reverb.

Triple Cheese by u-He uses comb filter modelling to create sounds - and it's free

It looks different, but it sounds surprisingly powerful, the trick being the minimal amount of processing power it consumes for the sounds it can create. The presets are pretty cool, too – and not all as cheesy as the name suggests.

Tyrell N6

Probably one of the most famous freeware synths, Tyrell Nexus 6 does a lot more than providing the soundtrack for watching C-beams glitter in the dark near the Tannhäuser Gate; it was designed originally as a hardware concept from German magazine – before the scale of producing it became apparent, and u-He created it in software for free distribution.

Tyrell N6 - free virtual analogue syntheszier

It’s been updated a couple of times, and though dated is still stable on current systems; a rock-solid classic virtual analogue with lush sounds from a two-oscillator variable waveshape model with sub-oscillator; it’s really easy and satisfying to program, too.


discoDSP developed the Discovery and Discovery Pro softsynths, which are virtual-analogue models with patch compatibility with the Nord Lead 2/X and the useful bonus of acting as patch editors for those synths too. Discovery isn’t free (though you can download a demo version that is less limited than most demos – enough to play with), but there is a free synth on their site.


OB Xd synthesizer VST - a free Oberheim X

OB-Xd is an emulation of the original Oberheim X, with a few enhancements. It’s been ported to many platforms, but discoDSP are maintaining it for Mac/Windows and also produce an iOS version.

It’s quite minimalist – befitting the original – and ideal for brittle, raw, loud synthwave tracks. Presets are selected through a pop-up window; the origins of OB-Xd away from UI guidelines and Cubase media libraries is very obvious, but hey – at least you’re not loading a patch from a C15 tape…

V2.2 of OB-Xd has now been released with HiDPI support/retina skins, and a lot of other improvements.

Martinic – Kee Bass

Fans of combo organs, obscure effects and tolex-wrapped warm circuits will feel comfortable on Martinic‘s site; the plugins are the sort of things real musicians cut their teeth on before they could afford the kit that’s become legendary today.

Martinic Kee Bass - free VST of the Rheem Key Bass string/bass synth

Next to the wonderful (paid for – but trials are available) duo of the Elka Panther combo organ and Lem Italian tape echo is a quirky little beast, the Kee Bass. This baby string bass synth is an obscure – but apparently easily to find – electronic instrument from Rheem, a company known for making water heaters. Martinic’s free plugin has probably done more to raise global awareness of this unusual-looking creature than anything else.

What you get is a solid-sounding monophonic bass/string organ with some extra tuning and filtering flexibility under the toggle switches and tolex. And of course, that super-distinctive throttle-style bass booster. It’s warm, and heavy, and full of character. And it offers polyphonic mode too – something the original never could.

It’s free, but you do need to request a licence before installing it. No catch, no signup, no involved account creation, it’s quick and straightforward. And absolutely worth the effort.

Martin Lüders – PG-8X

This is a stealthy one, but you really want it if retrowave is your thing – you can download a virtual Roland JX-8P here. The Roland JX-8P was a six-voice polyphonic, dual-DCO analogue synthesizer with sophisticated programming (but, more 1980s chips-and-software involved instead of analogue circuits) hidden behind a true 80s-tastic membrane button front panel. Most people needed the PG-800 programmer to get the most from it. It also provided the voices of the Roland GR77b bass guitar synth, and formed half of Roland’s impressive SuperJX, the JX-10 and MKS-70 module.

PG-8X - a virtual JX-8P with 12 voices

Martin’s free PG-8X VST – available for Mac OS and Windows, and as a standalone app as well – recreates the vital PG-800 programmer and includes a 12-voice JX-8P; not quite a SuperJX or MKS-70, but certainly everything that really mattered sound-wise apart from the two-layer ‘chase play’ function, which you could emulate with some MIDI effects and two instances of PG-8X.

It sounds clean, and appropriately digital yet still with the analogue filtered warmth and lush brass and pads I remember from my SuperJX – without the noise, flaky connections that made using 80s synths so much ‘fun’ in my old studio.

Or the sticky buttons. Or aftertouch repair.

Unlike many VSTs, it relies on you loading some presets into it from JX-8P sysex files. There are loads available, factory sounds and other libraries, and it’s straightforward. MIDI learn allows rapid mapping of controls from your hardware, and when you’ve loaded some sysex files and patches you can store the full 128-sound bank in a PG8X preset file for quicker recall.

It’s fast, lightweight, with easy to read controls and exactly the right aesthetic for the JX-8P; it’s also a synth Roland has yet to emulate in Roland Cloud. A must-have for ’80s pop, synthwave and early alternative electronic music.

Native Instruments – Komplete Start

This one’s really aimed at supporting hardware – but it’s available to all, and contains some very worthwhile, versatile instruments in an impressive 6GB library. Literally offering a complete start to Komplete, there are over 2,000 editable presets from such diverse sources as the Reaktor Player’s flexible synths – Mikro Prism, Reaktor Blocks, Newscool and Carbon 2, plus samples from several Komplete libraries.

They are limited versions of what Komplete offers, but they’re not restricted – just less complex – and have plenty of potential for playing with building your own modular synths, adding eerie drones and funky, up-to-date sounds to your productions.

Vember Surge

Surge is an open-source, multi-platform software synthesizer of remarkable power and flexibility, albeit with a user interface that’s best described as ‘functional’. What it lacks in style it more than makes up for in accessibility, though, as everything’s clear, legible, and scalable.

Surge open-source synthesizer

Once a very well-respected commercial project that cost over £150, it’s now free, community developed and growing in support, polish and capability.

The windows don’t always fit the VST panel and it’s a bit homebrew-feeling to use with a GUI that’s well over a decade old and designed for smaller, simpler screens (not necessarily a bad thing), but it sounds fantastic, includes a versatile effects chain, and in theory could be the only synthesizer you need. Which is quite scary given how much you could be spending…

Windows and 32-bit?

K Brown synth plugins

Who is K Brown? The about page credits Martin Vicanek for some code, but otherwise this appears to be a generous gift and a lot of effort from someone without any need to self-promote. It’s like the internet used to be… Unfortunately that means you need a computer like computers used to be – a Windows 32-bit machine.

Admire the collection of ‘inspired by, but not necessarily accurate recreations’ here. K Brown VSTs

TAL U-NO 62, Bassline & others

TAL are well-regarded for their Roland-esque plugins, with many users claiming they’re better than even Roland’s own software recreations. The latest versions are very reasonably priced, but if you’re using an older computer the deprecated, unsupported plugins are freely downloadable, and give a taste of what you can expect from their replacements.

Windows is well supported here, but for Mac owners, this is 32-bit only territory. Perfect for a repurposed old computer.

There are many more VSTs I can feature here, so come back for updates – these are the highlights of years of searching and messing with computer music with no professional intent.

Hardware: old computers are great instruments

My main Cubase machine is a 2013 iMac – at the time of writing it’s seven years old; that’s like the difference between a Commodore 64 and an Atari Falcon in old-school terms. It’s not running Catalina, because that breaks too many old apps, but it can. It’s an i5, too, mid-range, with no SSD.

It can run everything I throw at it, but too much Roland Cloud (System 8) and effects can upset it partly because it’s got seven years of junk piled in that system folder.

You can make use of all kinds of old machines, though.

No DAW? No problem?

There are several free DAWs now, so you don’t need Cubase or similar. For audio unit plugins (many of the ones mentioned above have AU versions) you can get going with Garageband on Mac OS, which is a really easy-to-use way of making music with your computer and completely free since introduction – so whatever age of Mac you have, you can get Garageband, albeit some older ones may be harder to find now.

For quick-and-dirty solutions, UglyVSTi by reFuse software is my go-to VST host for Mac – it tolerates 32-bit and even outdated VSTs; it can load NeuronVS on 10.14, for example. Just connect your MIDI controller and select the audio outputs, and go. All it does is turn the VSTi into a stand-alone instrument, no effects or anything.

For Windows, vstHost achieves the same results.