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The best free VST compressor plugins 2021: must-have dynamics processors for your DAW

Best free VST compressor plugins 2021
(Image credit: Various)

Compressors are essential tools for producers and engineers working in any genre, which means that they’re some of the best free VST plugins to have in your arsenal. While a compressor is unlikely to be a new producer’s first VST purchase, for many it’s the tool that separates the noob from the pro.

Perhaps more than any other technique, knowing when and how to correctly deploy compression is what marks a ‘producer’ out from being just another amateur messing around in a DAW.

On the surface, compression is a pretty straightforward effect - it’s simply the process of ‘squashing’ an audio signal. Basically, a compressor will attenuate the loudest peaks of a signal once they cross over a defined threshold, thereby reducing the dynamic range, which can allow the overall volume to be raised to make the resulting track sound louder or fuller.

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In reality, there are numerous variations and approaches, capable of creating differing effects suited to a range of different applications. Let’s quickly unpick some of the main points of difference.

One of the main divides in compressor types are those described as transparent and those that are ‘characterful’. Transparent compressors aim to do their job without you noticing they’re there, controlling dynamics but remaining as faithful as possible to the input audio. 

Characterful compressors, which are often emulations of vintage hardware, may alter the sound of your audio slightly, usually through subtle EQ or filtering, or by adding a touch of musically-pleasing distortion.

Then there are broadband or multiband compressors. The former tackles the whole frequency range at once, while the latter can be applied to low, high or mid range frequencies independently.

We’ve included some plugins labelled as limiters below, too. A limiter is essentially just a compressor set at a high ratio - ie, the amount of compression applied above the threshold - so that it completely cuts off all peaks over a certain level.

You’ll also come across terms like upward compression and expansion, both of which flip standard compression on its head. Upward compression still reduces dynamic range, but does so by raising the volume of quieter elements, as opposed to attenuating louder ones. 

Expansion, meanwhile, is a similar process but one that serves the opposite purpose to compression - increasing the dynamic range of an audio signal rather than squashing it.

Fortunately, the freeware realm has all of these compressor types covered, and if you’re confused about how and when to apply each the best thing to do is simply download a variety and experiment. In our round-up below, we’ve tried to include as broad a range of free compressors as possible for you to get your teeth into.

The best free compressor plugins 2021

1. Audio Damage RoughRider 3

The best free VST compressor plugins

(Image credit: Audio Damage)

PC/Mac/iOS | VST/AU/AAX

RoughRider is described by its developer as ‘one of the most popular dynamics processors on the planet’, and we don’t doubt that claim - this is an undeniable freeware classic. While version 3 adds a few new tools, this remains a pleasingly straightforward dynamics tool, with a clean and easy-to-understand UI that makes dialling in compression quick and simple.

The main USP here is the extremity to which you can push the effect. The Attack setting ranges from 0 to 100ms and the ratio can be dialled right up to 1000:1. Because of this, it’s great for punching up percussion loops as well as dialling in ‘New York’ style parallel compression.

V3 adds a Full Bandwidth mode, which disengages the ‘warming’ filter included in the original design. An external sidechain option rounds out the feature set.

RoughRider is neither the most characterful or most complex plugin in this list, but it’s simple, sounds great and is versatile enough to cover the bulk of your day-to-day compression needs.

2. MeldaProduction MCompressor

The best free VST compressor plugins

(Image credit: MeldaProduction)

PC/Mac | VST/AU/AAX (As part of the MFreeFXBundle)

If RoughRider is a little simple for your tastes, the MCompressor might be the answer. While many of the controls here are standard compressor fare, such as Attack, Decay, Ratio and Threshold, MCompressor stands out from the crowd thanks to its customisable curve editor.

This editor gives users lots of flexibility to define how the dynamics processor affects signals above or below the threshold level. You can, for example, use it to adjust the knee (ie abruptness) of the compression around the threshold, or to set multiple threshold points to engage two-stage compression. The editor also allows MCompressor to act as an expander or maximiser effect.

The plugin offers a range of up-sampling options, too, allowing for pristine sound quality. In all this is a very handy tool both for mastering and creating custom dynamics.

3. Tokyo Dawn Records Kotelnikov

The best free VST compressor plugins

(Image credit: Tokyo Dawn Records)

PC/Mac | VST/AU/AAX

The first of two TDR plugins in our roundup, Kotelnikov is a mastering compressor with some nifty advanced tools that mean it can adapt easily to a variety of uses.

First up is a sidechain high-pass filter - labelled Low Freq Relax - with both cutoff and slope controls that make it easy to fine-tune the extent to which your input’s low end triggers the compressor.

There’s a flexible Stereo Sensitivity parameter, too. With this set to 0% Kotelnikov responds only to a summed mono version of the input, while at 100% it will respond to whichever of the left or right channel is currently louder. The plugin has a dial labelled Peak Crest, too, which lets users balance between Peak and RMS compression responses. There are individual Release controls for Peak and RMS as well, which is a nice touch.

4. Klanghelm DC1A

The best free VST compressor plugins

(Image credit: Klanghelm)

PC/Mac | VST/AU/AAX

DC1A is one of the most basic-looking plugins in this roundup, but you shouldn’t hold that against it. The main controls here are limited to just input and output level dials – simply crank the former until the compressor engages as desired, then adjust the resulting levels with the latter.

There are four additional settings that add extra flexibility, though. First up, Deep engages a sidechain high-pass filter so that the compressor’s triggering ignores low frequencies. Relaxed, meanwhile, switches between Peak and RMS mode, while Dual Mono mode treats the left and right channels individually. Most interesting is Negative mode, engaging negative ratios for more extreme pumping response.

Despite the simplicity, DC1A is packed with winning sonic character and is a great tool for adding an element of faux-analogue to tracks in your DAW. Cranked up it can impart a nice touch of saturation, and despite the lack of Attack/Decay controls, it can be punchy enough for parallel drum treatments.

5. Klanghelm MJUC JR.

The best free VST compressor plugins

(Image credit: Klanghelm)

PC/Mac | VST/AU/AAX

Much like Klanghelm’s other freeware compressor, MJUC JR. trades on simple controls and sonic character. Like its paid bigger sibling, MJUC, the JR. is an emulation of Manley’s sought after Variable Mu Limiter Compressor hardware.

There are many commercial Vari-Mu clones on the market, and while MJUC JR. lacks the bells and whistles boasted by many of them, it can certainly compete sonically. This plugin is great for adding that mythical compression ‘glue’ to busses, groups or full mixes. It can add a lovely hint of saturation too, which is great for subtle harmonic enhancement of mid and high frequencies.

6. Tokyo Dawn Records Molotok

The best free VST compressor plugins

(Image credit: Tokyo Dawn Records)

PC/Mac | VST/AU/AAX

Based on the same processing tools as TDR’s paid Molot GE compressor, Molotok is a characterful dynamics plugin that offers a broad assortment of vintage-inspired sounds rather than emulating any one hardware device.

While the main controls are fairly standard fare, Molotok offers flexibility in the form of 11 distinct compression algorithms. These get progressively more aggressive as they go, ranging from a subtle and transparent squash up to characterful, heavy compression.

As a result, Molotok can successfully turn its hand to a range of mixing tasks, from adding punch to drums to beefing up thin instrument recordings. Clear metering and a user-friendly interface make this a nicely approachable plugin, too.

7. FXpansion DCAM FreeComp

The best free VST compressor plugins

(Image credit: FXpansion)

PC/Mac | VST/AU/AAX

First released back in 2012, FreeComp remains one of the most popular freeware plugins on the web. This is a circuit-modelled emulation of the compressor from ‘a classic British mixing console’ (ie, SSL). Much like its hardware inspiration, it’s at its best used on groups and busses as a way to tighten up mixes with some subtle ‘glue’.

There’s not a lot here that builds on the somewhat simple controls of the hardware it’s inspired by, but it gets the job done and sounds great. For a free and simple source of that sought-after ‘mix glue’, FreeComp remains hard to beat.

8. Xfer Records OTT

The best free VST compressor plugins

(Image credit: Xfer Records)

PC/Mac | VST/AU/AAX

As its name would suggest OTT, from Serum developer Xfer, is not a plugin generally associated with subtlety. This is a multiband upward/downward compressor that specialises in smashed, pumping and aggressive sounds.

This is the sort of plug you’ll either never use, or never be able to live without again. If you’re making delicate neo-classical recordings then you can probably skip downloading this one, but if hard-hitting electro or festival-ready EDM is your thing then there’s a chance you’ll never create another track without this.

Rather than the standard dynamics control offered by usual compressors, OTT is best used for making weaker sounds pop out of a mix. It’s handy for making vintage loops feel more modern, and its multiband design means it’s good for ramping up the presence of just the high, low or mid frequencies of a track.

9. D16 Frontier

The best free VST compressor plugins

(Image credit: D16)

PC/Mac | VST/AU/AAX

Frontier is a hardware-style limiter capable of being deployed for both transparent dynamics control and more creative uses. Loaded on a track or buss with levels set to subtly nudge the threshold, it can roll off peaks cleanly. With the input cranked, however, it can sound great for more overt limiting with an optional Soft Clip for the resulting distortion.

As with most limiters of this kind, the range of controls is fairly spartan, but modern touches such as automatic gain compensation, MIDI learn and a preset browser do add to the flexibility.

10. Native Instruments SuperCharger

The best free VST compressor plugins

(Image credit: Native Instruments)

PC/Mac | VST/AU/AAX

Included as part of NI’s free Komplete Start bundle, SuperCharger is a virtual tube compressor that sits somewhere on the divide between dynamics effect and saturation plugin.

The controls are pretty limited here, with Input Trim, Dry/Wet Mix and a central Compress dial doing most of the heavy lifting. Punch and Dirt modes do offer some control over the quality of the effect, but realistically, if you want fine-tuned dynamics there are many better options in this round-up.

What SuperCharger is great at is imparting a lovely touch of flattering distortion. Driven hard and used in a parallel setup it can be fantastic for adding a touch of gritty presence to bass-heavy kicks, or for slightly roughing up drums.

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