Freeware - Baconpaul TwoFilters VST Plugin

https://github.com/baconpaul/two-filters/releases/tag/Nightly

Two Filters, Two Step Sequencers, and some fixed mod paths.

Freeware - Consint Pult EQ VST Plugin

https://github.com/consint/Pult-EQ/releases

Pult EQ is a free and open source Pultec style tube EQ VST3 plugin (64bit) for Linux and Windows. Pult EQ is not made for fine detailed work, but for adding mojo and sound coloration. You can boost the lows, the highs and the mids. You can saturate your sound or, of course, do the “Pultec trick”. The EQ features stereo and mid/side processing and the saturation comes with automatic gain compensation and up to 16 times oversampling.

Freeware - Ghost Note Audio Spectrum Thief VST Plugin

https://ghostnoteaudio.uk/products/spectrum-thief

Spectrum Thief is an EQ-matching plugin that can import and export impulse responses. Great for capturing the frequency response of speaker cabinets, or creating adjustment filters to tone-match your guitar tone (or even a full mix), to a reference sound. The plugin is FREE and requires no authentication or registration, so grab your copy!

Freeware - Analog Obsession Poortec VST Plugin

 https://www.patreon.com/posts/poortec-119632465

Pultec style EQ Free

Freeware - Newfangled Audio Obliterate Filter VST Plugin

https://www.newfangledaudio.com/obliterate

Obliterate started life as a filter, but there was a bug in the code. We could have fixed that bug, but we let it fester. Over time that bug grew and mutated. It gained new powers and its anger warped them to its evil will. Seven years after that initial bug Obliterate can't be described as a filter at all. Obliterate is more like a new form of resonant distortion. Use cautiously. Use sparingly. And always clean up afterward.

Freeware - BPB Bassaturator VST Plugin

https://bedroomproducersblog.com/2024/11/26/bassaturator/

BPB Bassaturator is a free VST plugin for bass processing. It uses a push-pull style equalizer and three different saturation types to turn boring bass sounds into fat basslines that cut through a mix.

Freeware - Little Audio Little EQ VST Plugin

https://little-audio.com/

Little EQ is an equalizer plugin that brings to life the sound of a passive filter and an output transformer.

Freeware - Chris Liepe Vocal Menace

https://www.mymusicalvoice.com/p/vocal-menace-by-chris-liepe

ALL-IN-ONE Vocal Processing 

 -Multi-stage compression and limiting (no clipping) 

 -Several flavors of progressive drives and distortions 

 -Air and EQ 

 -A unique approach to Reverb 

 -Tempo sync'd and variable Delay 

 -Easy internal effects side chain

Freeware - Outobugi VST Plugins

https://outobugi.com/

Refire, Dynastia, Clamp, Wave, Extend, Dynastor, Termos, Dualcut, Toner

Freeware - Sky Blue EQ4 VST Plugin

https://github.com/Kiriki-liszt/Sky_Blue_EQ4?tab=readme-ov-file

Sky Blue EQ4 is maag-like tone shaping eq. Runs in double precision 64-bit internal processing. Also double precision input / output if supported. Internal sample rated fixed at 192/176.2kHz in 48/44.1kHz, 96/88.1kHz, 192/176.2kHz sample rates. It does run under 44.1kHz, but may have some EQ curve cramping. At 48/44.1kHz - x4 oversampling is on with 24 sample latency, and at 96/88.1kHz - x2 oversampling is on with 12 sample latency. Windows and Mac, VST3 and AU.

Freeware - Audiority The Sword EQ Boost Pedal VST Plugin

https://www.audiority.com/shop/the-sword/

Based on the same EQ/BOOST section of our Solidus VS8100, The Sword is the ultimate clean booster you’ll ever need! Clean boosters are basically a combination of tone shaping and amplification. We provided you a 10 band equalizer followed by a transparent clean booster for endless tonal shaping possibilities.

Freeware - smacklabs SL84 Console EQ VST Plugin

https://smacklabs.wordpress.com/2017/03/08/sl84-console-eq/

Based off of a British “80 series” console module EQ, the SL84 captures the sound and its Rock n Roll vibe of this vintage piece of hardware. Using IR technology for the design, the SL84 features true frequency response of the original hardware module. Just adding the SL84 on every track of your session will add a subtle effect on your project.

Freeware - Analog Obsession ATONE VST Plugin

https://www.patreon.com/posts/atone-102446579

A Channel Strip with A-Type EQ, Filters and 436 style Compressor 

It has lots of capabilities for tone shaping with its own custom design and internal routing.

There is no line or mic preamp as an input module but INPUT knob will drive EQ circuit's Gain Trim to get nasty op-amp saturation. 

Compressor section based on 436c with extra modifications. Compressor has AMOUNT knob to compression and make-up gain. So, it will be gain compensated.

Freeware - ZL Audio ZL Equalizer VST Plugin

https://zl-audio.github.io/plugins/zlequalizer/

ZL Equalizer is a 16 band equalizer plugin with the following key features: 

 Multiple Filter Settings: Supports 16 frequency bands, 8 filter types, 5 stereo modes, 7 variable slopes and 2 filter structures. 

High-Quality Sound: With 64-bit floating-point processing and de-cramping technique, outstanding performance is ensured in both low-end and high-end. 

Adjustable Dynamics: Adjustable threshold, attack, release, and side-chain frequency, etc. 

Carefully Designed Interface: Interactive spectrum graph, smart collision detection, and smooth animations.

Freeware - Lorus Sound Aerial EQ VST Plugin

https://www.lotus-sound.ch/aerial-eq

Introducing the new AERIAL EQ, an innovative semi-parametric tube equalizer plugin that elevates your audio experience to new heights. Crafted with precision and creativity in mind, this plugin offers a unique feature set, including the distinctive "Air" function.

Freeware - Venn Audio Free Suite VST Plugins

https://www.vennaudio.com/free-suite/

Free Suite is a completely free, performant, light weight, resizeable, zero fuss set of cross-platform audio plugins. All the tools needed to fully mix a track to professional standards. No registration needed, simply download and enjoy! Free Suite is available for Windows, Mac, Mac M1 native and Linux, in VST3, AU and AAX formats.

Freeware - Ohmforce Frohmager Filter VST Plugin

https://www.ohmforce.com/frohmager

Released in 2001 and maintained for 20 years, Frohmage filter has from the beginning been an insanely popular free filter with millions of cumulated download. Forhmager is enriched with a modulation matrix that leaves nothing to desire along with their brand new Macros System.

Freeware - Bertom Audio EQ Curve Analyzer VST Plugin

https://www.bertomaudio.com/eq-curve-analyzer.html

EQ Curve Analyzer is an analyzer and signal generator plugin to see the frequency response (magnitude and phase) of any plugin or hardware. Insert the plugin you want to analyse between two instances of EQ Curve Analyzer, the first one set as a signal generator and the second one as an analyzer. Then adjust the latency if needed. That's it! It is particularly useful as a learning tool to see what classic EQs emulations are doing for example. It also features a "group" system that allows you to compare two analyses in real-time on the same graph.

Freeware - Viator Radiant Q EQ VST Plugin

https://viatordsp.gumroad.com/l/uxpzms

Introducing Radiant Q - A Tube EQ Plugin for Audio Excellence Elevate your audio production game with Radiant Q, an exquisite plugin that pays homage to the legendary tube-based equalizers of the bygone era. Immerse your tracks in warmth, character, and vintage charm as you rediscover the magic of classic analog sound.

Freeware - Hz Box by Higher Hz VST Plugin

https://higherhz.com/hz-box/

Hz Box is a free algorithmic soundbox emulator plugin that adds character by changing the timbral quality of any sound. The plugin can help define a sound’s place in your mix by giving it the richness and depth it needs.
Hz Box can also bring flat sounds to life with a little brightness and just the right amount of sparkle. Since we’re taking the concept of what a real-world soundbox does to sound, Hz Box can make subtle character changes or create an entirely new tonal profile.