The 11 Best Free Compressor Plugins 2024 (SSL, Vari-Mu, Opto..)

Top 11 Free Compressor Plugins |

Among the sea of free plugins that is the internet, we venture to find the 11 best free compressor plugins.

Compressors are one of the crucial effects in music production, from the very early mixing to the final mastering session. A good compressor can be the difference between a smooth, dynamic track and a harrowing mess. But that’s not it; using a proper compressor for the right purpose can make your job much easier.

Hence, in this article, we have compiled multiple varieties of compressors, including the ultra-fast digital, coloring mastering compressors, the classic vari-mu, etc. Our suggestion would be to identify which kind of compressor you require and selecting one from each category. Of course, an honest try of each is the best way to decide..

Now, without further ado, let’s get on with our list..

The 11 Best Free Compressor Plugins 2024

1. Analog Obsession BUSTERse (SSL Compressor)

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Analog Obsession’s BUSTERse plugin can be your main tool for “gluing” mixes.

Now, what do you use the bus compressor for anyway? First, it allows you to shape transients, and second, to get the effect of “gluing” the mix as a whole. The SSL Bus Compressor is a very popular equipment for this, which was part of the console. But now, there are enough plugins that emulate its operation.

Such is the free software BUSTERse from Analog Obsession. Its main feature is that, in addition to the compressor settings, it has many additional features that will help you affect the character and dynamics even more. Let’s now try to take them all apart.

20 Best FREE Mixing VST Plugins For Musicians 2022 |

Key Features:

  • Familiar Compressor Settings

If you already have experience with SSL-style compressors, then the set of basic settings will not discourage you. In particular, there is the usual Auto Release, Ratio from 1.5 to 10, Attack from 0.1 to 30 milliseconds, Make-Up Gain, and Threshold control.

  • Dry/Wet Control

Unlike many paid plugins, the developers have also implemented the Mix knob, which implies selecting the ratio of Dry and Wet signals. This parameter can be very helpful if, for example, you want to do a parallel compression for drums.

  • Additional Mods

At the top right of the plugin window, you will get three buttons that are responsible for mods. In particular, the first Main will work like the usual bypass. Also, here is the Turbo, which will bring the plugin to work more similarly to the original unit. And in addition, there is an Xformer mode to get more saturation.

  • Sidechain Filter

The Sidechain section makes your work with the plugin most exciting. You can use it to influence how the compressor perceives frequencies. For example, there is a High Pass Filter here and two Mid and HF knobs.

  • Transients Shaping

On top of that, the Sidechain section has another set of TR controls to help you influence the transients a bit more. For example, you will find a Tilt control that will boost the high frequencies and cut the lows, or vice versa. In addition, there are also separate Mix and Boost knobs.


Analog Obsession BUSTERse is available for Windows 7 or higher and macOS 10.9 or higher. It comes in VST/3 and AU formats.


Analog Obsession’s BUSTERse plugin may seem a bit complicated at first. But if you learn how to use it, it can become a powerful tool for bus compression. This software will allow you to “glue” the mix and influence the transients in the best way. And the fact that it’s free is wonderful.

2. Variety of Sound density MKIII (Mastering Compressor)

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Density MkIII is a smooth bus compressor ideal for gluing groups of instruments.

Variety Of Sound has developed many free plugins, and their Density MkIII is one of the most valuable plugins. While the sound may not exactly be akin to analog, the interface is designed to look similar to hardware bus compressors. You might find it handy for compressing sub-mixes.

Variety of Sound density MKIII - The 11 Best Free Compressor Plugins |

Key Features:

  • Stereo Processing

The plugin features three processing modes: L/R, Stereo, and M/S. In L/R mode, the left and right channels are processed separately, whereas they are linked in Stereo mode. And similarly, in M/S mode, you can process the mid and the side signals separately.

  • Side-Chain

The plugin lets you target the incoming audio signal or an external side-chain source by flipping the SC switch. Similarly, you can engage a limiter mode, which has a higher compression ratio. Note that it’s not a brick-wall limiter.

  • Timing & Range

Density MkIII features six “timing” modes, setting the attack and release time to preset amounts found in esteemed hardware compressors. Similarly, the Range knob controls the maximum level of compression the plugin applies. Use it if your bus has loud but inconsistent transients that need preserving.


The plugin is available for Windows 7 or higher for both 32-bit and 64-bit. It comes in VST 2 format.


The controls in Density MkIII can be a little limiting when compared to other compressors. However, if you like the smooth sound, the plugin is well worth keeping. The Range parameter also helps preserve loud transients, like drum strikes.

3. Analog Obsession VariMoon (Vari-Mu Compressor)

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VariMoon is, you guessed it, an emulation of a vari-mu compressor.

Analog Obsession has been making emulated plugins for a while. And VariMoon is modeled after the legendary Fairchild 660 compressor. It features an easy-to-use interface with deep component emulation to deliver authentic sound. However, the interface differs by a good deal.

VariMoon has a fixed attack of 10 ms with six positions for the release, including two auto modes. Before talking more about VariMoon’s features, we would like to point out another Analog Obsession’s bus compressor BUSTERse, a great free stereo compressor with EQ and side-chain.

Analog Obsession Varimoon Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Variable Input

As a vari-mu compressor, variable input is what it’s all about. So, the first knob, Input Attenuation, lets you set the input drive from -18 to +18 dB. You can use it to drive the internal circuit and get saturation. In addition, it also features a high-pass filter labeled HPF that has a range of 20 Hz to 500 Hz.

  • Threshold

A feature that plugins of this nature don’t provide is a separate threshold. However, VariMoon employs a ratio control (DC Threshold) and an actual threshold (AC Threshold) with a range of 50 dB. It’s crucial if you want clean compression without a driven input.

  • Oversampling

Finally, the Analog Obsession logo lets you enable a 4x oversampling to help you avoid aliasing caused by the saturation. However, since the plugin is relatively modest when it comes to saturation, you can get away without oversampling in most cases to save CPU.


VariMoon is available for Windows 7 or higher 32-bit and 64-bit and macOS 10.9 64-bit only. It comes in VST 2/3 and AU formats.


If you are after an analog-sounding compressor with plenty of features, look no further from VariMoon. The relatively fast attack makes it more of a clipping compressor than a gluing compressor, though. So, you will benefit from using it on vocals, instruments, and drum stems if you are looking to reduce harsh transients.

4. Analog Obsession Britpressor (Vintage Compressor)

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Get the sound of the Beatles and early Pink Floyd with this plugin.

Britpressor is an emulation of the classic British channel compressor that was the sound of many hit albums from the 60s and beyond. The plugin is actually a part of a three-plugins bundle called BritBundle, which includes a preamp/filter, a compressor, and a complete channel.

Analog Obsession Britpressor Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Limiter

The plugin features a limiter as well as a compressor. However, it doesn’t function well as a mastering limiter. Instead, it is much more preferable for clipping off drum busses or instrument tracks to keep everything under control. The second needle meter shows its gain reduction.

  • Built-in Preamp

The built-in preamp gives the plugin its warm sound. Furthermore, you can also drive the input using the three-band EQ provided. If you enjoy warm, saturated sounds, you can control which part of your frequency spectrum gets more treatment with ease.

  • External Side-Chain

In addition to everything else, it also features an external side-chain input, which is well known for ducking your synths or bass when the kick hits. Note that you can use the EQ we mentioned earlier to adjust the level of detected frequencies too.


Bitpressor is available for Windows 7 or higher 32-bit and 64-bit and macOS 10.9 64-bit only. It comes in VST 2/3 and AU formats.


Using channel plugins is a great way to save time. If you don’t own one yet, the BritBundle is a great starting point. Further, with Bitpressor’s 4x oversampling capability, you will always get pristine quality. Not to mention the handy mix knob for easy NY/parallel compression.

5. Integraudio & Sixth Sample Cramit (Multiband Dynamics)

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The 11 Best Free Compressor Plugins 2024 (SSL, Vari-Mu, Opto..) - 2024 Update

Cramit by Integraudio is a free multiband compressor and distortion plugin. 

The plugin combines the classic OTT sound with distortion effects, creating an interesting sonic character that you can use to add a new flavor to your mixes/productions.

With an easy and user-friendly GUI and parameters like Distortion, Drive, Type, Pre/Post buttons, Speed, Depth, etc., you can use the plugin for dynamic processing and interesting morphing and distortion effects.

Key Features:

  • Multi-band processing

Featuring a 3-band upwards/downwards compressor with expansion and solo/bypass options for each band, the plugin allows you to easily apply compression or expansion to specific frequency bands to achieve the desired sound effect. This feature can be particularly useful when balancing the mix or fixing issues with specific frequencies.

  • Harmonic processing

Cramit also includes a distortion section with seven different types and mixing controls. This feature adds a unique character to the sound and can help you achieve the desired tonal coloration. The distortion unit can be particularly useful for enhancing the warmth and grittiness of recordings, adding more depth and dimension to the sound.

  • Intuitional GUI

One of the standout features of Cramit is its user-friendly interface. The plugin features a simple and intuitive design that makes it easy to use, even for beginners. The interface provides insightful visuals that allow you to quickly and easily see the changes you make to the audio. This makes it easier to fine-tune your audio and achieve the desired sound quality.

  • Presets

There are ten factory presets that the plugin comes with that provide you with a starting point for your audio processing. These preset can be modified and customized to suit individual needs and preferences, making it easy to get the desired sound quickly.

  • CPU-efficient

The plugin balances functionality and usability while still being efficient in processing power. This is an important feature, as it ensures you can apply the necessary processing without encountering issues such as lag or system crashes.


Regarding compatibility, Cramit is designed to work on 64-bit or 32-bit VST3 or 64-bit AAX support on Windows 8.1 or newer and on 64-bit AU, VST3, or AAX support on macOS 10.9 or newer.


To summarize, the plugin’s interface, additional parameters, and presets are what works for it and give it an edge. In addition, it’s free, so it will cost nothing to keep it in your mixing arsenal. Overall, it’s a great alternative for OTT, with additional features that make it a versatile multi-band compression plugin.

6. AudioDamage Rough Rider 3 (Bus Compressor)

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Rough Rider 3 is a digital compressor that boasts a fabulous interface.

Having existed for over a decade, Rough Rider 3 remains a strong contender among the most reliable and quality compressor plugins. It features all the standard parameters you’d expect from a digital compressor and a filter to deliver a tube-like character. Note that it’s not a component emulation, though.

AudioDamage Rough Rider 3 Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Convenient

Rough Rider 3 packs all of the essential compression parameters in a neat user interface. The Sensitivity section, which is the threshold, also contains a gain reduction graph. Similarly, most of the other parameters are named without acronyms or analogies.

  • Warming Filter

The plugin features a “warming” filter, which sounds like a low-pass at around 12 kHz to help make the audio sound less bright or “digital.” However, if you don’t like its sound, you can turn it off by turning the button labeled Full Bandwidth on.

  • Side-chaining

The plugin features an internal side-chain high-pass filter and an external side-chain input. You can use the high-pass to avoid pumping effects caused by the kick, whereas the external side-chain is handy for ducking the bass or other instruments when the kick hits.


Rough Rider 3 is available for Windows 8.1 or higher, macOS 10.11 or higher, iOS 11 or higher, and Ubuntu 18 or higher. It comes in VST 2/3, AU, AAX, and IAA formats.


What we love about Rough Rider 3 is how it’s available in almost every significant OS. Hence, it is one of the most downloaded plugins on the internet. Its new transparent compression works well for gain leveling, and the nifty gain reduction meter helps visualize how much the plugin is affecting your audio.

7. Audio Tools Leveling Tool (Opto Compressor)

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This plugin is an emulation of a tube-based compressor from the 60s.

As you might have already guessed, we have another LA-2A emulation at hand here. However, despite the similar parameters, Leveling Tool sounds rather far from it. Instead, it has a unique flavor in its sound, and you can control how much of the character you want in your audio.

Leveling Tool has a needle meter that can display gain reduction or the output peak. Select either using the first toggle on the left of the interface. Speaking of which, we find the UI phenomenal to work with. It provides plenty of flexibility when it comes to compression.

Audio Tools Leveling Tool Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Side-Chain Filter

Add a high-pass filter to the signal the compressor is listening to using the SC HPF knob. You can use it to eliminate the pumping effect on bass-heavy sounds and make the compression more transparent. However, if you are limiting for mastering, it’s best to avoid using it.

  • Sonic Character

As we’ve mentioned, the sound of this compressor is unique and particularly interesting on vocals. You can use the Drive knob to increase the amount of tube saturation to your liking. This drive is supplemental to the internal drive generated by the audio gain itself. Also, make sure you use the 4X oversampling for extreme saturation.

  • Ratio Adjustment

Unlike the hardware LA-2A, Leveling Tool lets you adjust the ratio smoothly from 2:1 to infinity or limiting. Purists might be aghast over the idea of modifying the perfect ratio of the hardware unit. However, having this flexibility makes the plugin versatile and a worthy addition to your collection.


This plugin is available for Windows 7 or higher and macOS 10 or higher, for both 32-bit and 64-bit. It comes in VST 2/3, AU, and AAX formats.


We love how flexible this plugin is. In addition to everything we’ve mentioned so far, it also offers compression attack/release and a dry/wet knob for easy parallel compression. It makes Leveling Tool an appropriate compressor for just about every case.

8. TDR Kotelnikov (Mastering Compressor)

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Designed to be as transparent as possible, this mastering compressor is on par with most paid plugins.

Kotelnikov is the first on our list that doesn’t attempt to sound like any hardware unit. Instead, it is proudly digital, using the fast computing capability of computers to deliver the smoothest sounding compressor in the freeware market and beyond.

It employs an innovative mix of peak and RMS compression that lets it preserve the timbre and punch of the original audio. Furthermore, it also features extensive stereo processing options and oversampling to make the plugin that much more suitable for mastering.

TDR Kotelnikov Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • High-Pass Filter

The Low Freq Relax section features a high-pass filter that can vary from 25 Hz to 500 Hz. Further, it offers four steepness slopes: 0 dB/oct, 3 dB/oct, 6 dB/oct, and 12 dB/oct. The first one turns off the filter, whereas the last one is the steepest and useful for avoiding low frequencies completely.

  • Stereo Sensitivity

Despite what the name would lead you to believe, this knob doesn’t enable individual compression of each stereo channel. Instead, it is for controlling the stereo link of the detector. So, 0% means it only detects the mono signal, whereas 100% means it will follow the channel (left/right) with the louder audio.

  • Peak/RMS Threshold

The Threshold knob controls the RMS threshold value. So, you will have to dial in a fair amount to start compression. On the flip side, the Peak Crest knob sets the peak threshold relative to the RMS threshold. It can be positive or negative, where a positive value increases the peak threshold over the RMS threshold. Thus, the peak compressor becomes less sensitive.

  • Stereo Processing

The drop-down menu labeled “Stereo” in a default preset lets you select from six modes of stereo processing: Mono, Stereo, Sum, Diff, Left, and Right. Just to clarify, Sum and Diff are mid and side signals.

  • Oversampling

It’s worth noting that this plugin employs oversampling at all times. It offers two processing quality modes: Eco and Precise. Eco utilizes an internal frequency bandwidth of 100 kHz, whereas Precise uses 200 kHz of bandwidth. Interestingly, though, it only oversamples the detected audio, leaving the rest of the audio completely untouched.


Kotelnikov is available for Windows XP or higher and macOS 10.9 or higher. It comes in VST 2/3, AU, and AAX.


The amount of features this plugin offers is nothing short of awe-inspiring. Even with the long list of features we’ve enlisted, our article barely even scratches the surface of its platter of versatility. We highly recommend giving this plugin an honest try, even if you own many paid compressors.

9. Xfer Records OTT (Multiband Dynamics)

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Practically a household name, OTT brings a little delish to your sound.

Xfer Records’ OTT is a multi-band compressor and expander, which is all about making your sound fatter, cleaner, and overall better. Instead of providing you complete control, it employs a tried and true audio enhancement method to make everything sound rich instantly.

XFer Records OTT Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Three Bands

OTT has a low, mid, and high band for compressing each separately. However, you cannot change the bands’ frequency crossovers. As a general rule, use the low band for adding depth and the high band for overall clarity. The plugin uses a chain of FX to provide optimal results.

  • Saturation

In addition to compression, the plugin also features audio enhancers to add saturation to the audio. Each band has a unique kind of exciter to ensure the results you’d expect. Note that overdoing it can result in harsh sounds, so staying modest is a good idea.

  • Time Control

You have probably noticed the Time knob on the GUI. It controls the compressors’ attack and release times. However, since they are both tweaked together, treat the knob as aggressiveness control. Higher values result in a smoother sound, whereas lower values result in hard, distorted sound.


The plugin is available for Windows 7 or higher and macOS 10 or higher, both 32-bit and 64-bit. It comes in VST 2/3, AU, and AAX formats.


If you produce electronic music, this plugin is a must. It has a reputation for sounding harsh and aggressive, making it a perfect complement for EDM, hip-hop, etc. However, even if you produce other, softer genres, you can still use it to enhance vocals, synths, strings, etc.

10. Melda MCompressor (Versatile Compressor)

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If you are after something insanely flexible, you’ll want to check this plugin out.

Melda Audio has always been surprisingly generous in its free plugins lineup, and MCompressor is a fabulous example of it. It boasts a fantastic resizable GUI with detailed meters and a graphical display of your compressor’s parameters and channels.

In addition to being conveniently designed, it also features multiple channels, an adjustable knee, and a custom compression shape. We will talk more about its standout features next.

Melda MCompressor Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Multi-Channel

MCompressor supports up to 8 channels, making it ideal for sound designers working on 7.1 surround sound for films and games. However, it doesn’t stop there. MCompressor also features unlinked stereo and mid/side mode, making it an excellent choice as a mastering compressor.

  • Three Knees

The plugin has three knee shapes: Hard, Linear, and Soft. And you can also adjust the amount of the knee using the Knee Size knob. Of course, the Hard shape doesn’t let you have any knee at all, but Linear and Soft knee each enables you to create a straight line and a curve.

  • Compression Shapes

On top of the multiple knee shapes, you can also create a unique compression shape using a node-based editor. It lets you create smooth, curved compressions to intricate, rhythmic patterns. This flexibility makes MCompressor one of the best on our list.


The plugin is available for Windows 7 or higher 32-bit or 64-bit and macOS 10.9 or higher 64-bit. It comes in VST 2/3, AU, and AAX formats.


As one of the most feature-packed compressors on our list, we must laud MCompressor as a near-essential tool for every musician. However, it’s worth noting that installing this plugin requires you to download a bundle of plugins (which are also worth looking into).

11. TDR VladG Molot (Transparent Compressor)

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Rocking a Soviet Union-inspired theme, Molot is a coloring compressor with a tasty sound.

Molot is the opposite of transparent. Every feature imparts some sort of color and flavor to the audio, whether in the spectrum, dynamism, or saturation. However, that doesn’t make it a lousy plugin; quite the opposite. In addition to compression, it also features a limiter.

Similarly, it also features up to 8x oversampling for alias-free processing. And you also get a soft knee control, dry mix, and so on. However, as you’ll find out, it’s not the standard controls that make this plugin attractive.

TDR VladG Molot Review - Top 11 Free Compressor Plugins 2021 (VCA, Vari-Mu, FET, Digital) |

Key Features:

  • Stereo Modes

The plugin features seven stereo processing modes: Mono, 2 Mono, R.S.chn, Mid, Side, M/S, and Stereo. We’ll skip the obvious from our description. 2 Mono is dual mono, R.S.chan is a mono mode with external side-chain input, and M/S mode unlinks the compression on the mid and side signals.

  • Input Filter

The first knob, Filter, controls a high-pass filter on the input signal. You can set the frequency from 40 Hz to 260 Hz. Note that turning off the Filter doesn’t make the audio flat. Instead, it adds a smooth 3 dB low-shelf dip from around 500 Hz.

  • Alpha/Sigma Attack

The two attack modes change how quickly the compressor reacts after the attack time has been reached. In Alpha mode, the compressor is highly aggressive, whereas, in Sigma mode, the compressor takes much longer to start compression. Thus, if you want compression on the transients, Alpha mode is the way to go.

  • Mid Scoop

Another exciting feature is the Mid Scoop knob, which is a post-compression gain of multiple frequencies forming an intricate spectrum. For example, if you turned up the Mid Scoop knob, you will get a slight dip below 200 Hz, at 1.5 kHz, at 8.5 kHz, and a boost at 500 Hz, at 4 kHz, and above 12 kHz. However, the opposite isn’t true for turning the knob down. So, we suggest setting it by ear.


This plugin is available for Windows 7 or higher 32-bit and 64-bit and macOS 10.9 or higher 64-bit only. It comes in VST 2 and AU formats.


We love the sound of this plugin and how it colors the audio, especially with the Mid Scoop parameter. Of course, staying subtle is a good idea, but don’t shy away from experimenting with dramatic levels of processing either.

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