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The best VST/AU synth plugins 2021: the top analogue, wavetable, modular and free synthesizers

Native Instruments Super 8
(Image credit: Native Instruments)

For some musicians, the best plugin synths are the ones that come with their DAW, as they won't cost them anything over and above what they've already paid for their music production software.

However, many others choose to augment these built-in soft synths with third-party plugins - add-on instruments that either be purchased or, in some cases, downloaded for free.

In many ways, these work just like the hardware synthesizers that you’ll be familiar with, but they run in software instead of coming in a physical box. Some software synths are emulations of hardware models - recreations of vintage keyboards are particularly popular - but others are completely original.

You’ll hear software synths being referred to by a variety of different names - virtual instruments, software instruments or just plain old VSTs - but on a basic level, they all operate in the same way.

Once installed on your PC or Mac, each plugin synth can be loaded onto its own track in your DAW, enabling you to play and record it using your MIDI keyboard or other MIDI controller.

You can also program notes for it to play using your mouse, and each synth will come with its own set of controls for adjusting the sound.

Typically, you’ll find banks of presets, too: pre-programmed sounds that can simply be loaded up and played or used as starting points for further editing and sound design.

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VST or AU?

There are a variety of plugin standards out there, so before you buy any plugin synth, you need to make sure that your DAW is compatible with it.

On the PC, Steinberg’s VST (Virtual Studio Technology) is by far the most popular, and supported by pretty much all the major DAWs. You can get Mac VSTs, too (though it’s worth mentioning that not all Windows VSTs run on Mac), and Apple also has its own standard called AU (Audio Units).

You may also encounter standards such as AAX and RTAS, both of which are specific to Avid’s Pro Tools software.

Be sure to check compatibility with your specific computer hardware, too. For example, not all plugin synths currently offer native support for Apple's M1 Macs, though more and more are being updated to provide this.

There are so many plugin synths on the market these days that settling on a shortlist of 'best' ones is pretty much impossible, but we've given it a go. Below, you'll find what we consider to be the best choices in a range of different categories. You might not need all of them, but any one of them is likely to improve your music-making setup.

Best analogue synth plugin

u-he Diva
Mac/PC/Linux | VST/AU/AAX |€179

Best plugins 2020

(Image credit: Future)

There are probably more classic analogue synthesiser emulations peppering the plugin landscape than any other type of virtual instrument, from Native Instruments’ Monark Minimoog to Arturia’s magnificent and increasingly comprehensive V Collection of vintage beauties.

However, standing proudest among them is u-he’s venerable Diva, a semi-modular faux analogue synth that draws influence from a selection of legendary hardware in its roster of oscillators, filters and envelopes, and yields a sound utterly indistinguishable from the real thing.

Released in 2012, Diva later saw the addition of a Roland JP-8000-style digital oscillator option, but for us, it’s all about those VCOs, DCOs and stunning analogue filters.

Read u-he Diva review

Best wavetable synth plugin

Xfer Records Serum
Mac/PC | VST/AU/AAX | $189 

Best plugins 2020

(Image credit: Future)

Native Instruments’ genre-shaping Massive unarguably spearheaded the wavetable synth renaissance, but for the last half decade, Steve Duda’s Serum has been the go-to for producers of EDM and bass music.

There’s so much good stuff here that it’s hard to know where to start, but the headlines include dual wavetable oscillators with a variety of blending and morphing styles, spectacular unison voicing, a full-on wavetable editor, a huge menu of filter types, an intuitive but supercharged modulation system, and a rack of ten stunning effects modules. And the sound? Think punchy, animated basses; scintillating modulated pads; searing leads; and evocative FX.

An exemplar of 21st century synth design, Serum is nothing short of essential.

Read Xfer Records Serum review

Best hybrid synth plugin

Spectrasonics Omnisphere 2
Mac/PC | VST/AU/AAX | $499

Best plugins 2020

(Image credit: Future)

Can any synth ever really be definitively dubbed ‘the greatest of all time’? Probably not, but if one could, Spectrasonics’ software masterpiece would surely be a contender.

Not only does Omnisphere 2 offer over 500 analogue waveforms and digital wavetables, over 30 types for each of its two filters, 58 superb effects and an integrated granular synthesis engine, but it also comes with 65GB of top-notch sample-based sound sources for manipulation within its ridiculously powerful architecture – plus the ability to import your own!

Epic in scale and sound, Omnisphere 2 is a synth you could spend a lifetime with and still never tire of.

Read Spectrasonics Omnisphere 2 review

Best modular synth plugin

Native Instruments Reaktor 6
Mac/PC | VST/AU/AAX | $199/£179 | Buy at Native Instruments

Native Instruments Reaktor 6

(Image credit: Native Instruments)

Not just a synth, but a "modular DSP lab," Reaktor enables you to build your own synths, samplers, effects and sound design tools, and nods to the world of Eurorack with its Blocks patching environment. More than 70 instruments come included, and thousands more are available in the user library.

Reaktor 6 won't be for everyone - things can get very complex, very quickly - and if all you want is 'Eurorack in software' then there are probably better options (take a look at VCV Rack, a version of which you can download for free).

If you're keen to experiment and willing to negotiate a bit of a learning curve, though, it remains in a class of its own.

Read Native Instruments Reaktor 6 review

Best vintage synth emulation plugin

Arturia V Collection 8
Mac/PC | VST/AU/AAX | €599 | Buy at Plugin Boutique

Arturia V Collection 8

(Image credit: Arturia)

So many classic hardware synths have now been emulated in software that picking a single 'best' one is pretty much impossible. It really depends which vintage instrument you want and how much you're willing to spend.

If you want a whole bundle of classic keyboards, though, it's hard to look past Arturia's V Collection 8. Featuring emulations of instruments from the likes of Yamaha, Roland, Oberheim, Moog, ARP and many more, it's a veritable treasure trove of synth history, with each model recreated in exacting detail.

It's not cheap, but when you consider how much is in V Collection 8, its price looks pretty fair. In fact, there's enough vintage synth goodness here to last you a music production lifetime.

Read Arturia V Collection 8 review

Best free synth plugin

DiscoDSP OB-Xd
Mac/PC | VST/AU

discoDSP OB-Xd 2.0

(Image credit: discoDSP)

OB-Xd isn’t the flashiest free synth, and nor is it the newest, despite being updated to version 2.5 in recent months. It remains our favourite freeware synth, though, based largely on its blend of simple usability and excellent sound.

This is an emulation of Tom Oberheim’s classic OB-X polysynth, an analogue classic beloved for its thick, rich sound and easy-to-use interface.

OB-Xd lives up to its inspiration on both fronts. Sonically, this is up there with many paid analogue emulations and, while it lacks the bells and whistles of something like Arturia’s V Collection synths, OB-Xd does build on the design of the original with a morphable filter design and voice variation controls.

While other freeware synths are undoubtedly more adventurous or original than OB-Xd, none are likely to match the broad appeal of this excellent virtual analogue. Download it now and it could quickly become your go-to for rich, vintage poly sounds.

Download DiscoDSP OB-Xd

Best synth plugin under $100

Native Instruments Super 8
Mac/PC | VST/AU/AAX | $99/£89 | Buy at Native Instruments

NI Super 8

(Image credit: Native Instruments)

The competition at the budget end of the plugin synth market is fierce, but if you want a synth that sounds great, is easy to use and comes with loads of presets, NI's Super 8 might well be your best option.

This is inspired by the grand old polyphonic beasts birthed by Roland, Korg, Sequential Circuits et al in the '80s. In terms of sound, though, Super 8 beefs things up somewhat, yielding the kind of weight demanded by contemporary producers without losing the essence of the 20th century synths that inform it.

In these days of overachieving ‘powersynths’, with their endless screens and controls, and mind-altering, hyper-real sonics, it’s quite amazing to think that Super 8’s relatively rudimentary feature set would once have been perceived as state-of-the-art.

But that simplicity is a major part of the attraction: this is pure ‘what-you-see-is-what-you-get’ old-school synthesis, with no architectural distractions from the mixing, voice-stacking, modulating and filtering of analogue waveforms in the pursuit of massive basses, lustrous pads, searing leads, picturesque keys, chrome-plated percussion, and all those other quintessential monophonic and polyphonic electronic tones. 

Read Native Instruments Super 8 review

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