Big-Sur Diode Clipper

Big-Sur is a freeware emulation of a diode clipper guitar pedal. There’s no information on which specific guitar stompbox is emulated, but the plugin seems to be based on the classic Big Muff distortion pedal. The developers describe Big-Sur as a stompbox that is suitable for distorted rhythm guitars and heavy leads, with a wide distortion spectrum and plenty of fuzz.
he interface features a bypass switch, four control knobs (Sustain, Level, Tone, and Mix), and two on/off switches – one for the Tone control and one for the oversampling feature. The user can also adjust the GUI size (from 80% to 125%) and control the graphics quality (useful for reducing the RAM usage).

https://fuseaudiolabs.com/#/pages/product?id=300982337

occularScope

OccularScope is a bar or beat synchronised oscilloscope with side chain input.

• View either a single beat or bar synchronised to your DAW
• Line or filled waveform view
• Can show side chain input overlaid or added to primary input
• Freeze button
• Fully scalable user interface
• Dark and Light themes (or completely customise your own colour scheme)

Plasticity filter

PlasticityFilter is a dual mode filter offering a simplified interface to its high and low pass filters or a more complex mode of operation allowing complete independent control.

• Simple mode with single frequency, resonance and drive controls offering high and low pass filtering.
• Expert mode with independent controls for the high and low pass filters.
• 12 or 24dB/oct Ladder filters.
• Drive control ranging from subtle saturation to extremely overdriven sound.
• Filter frequencies can be linked in expert mode with variable separation amount for bandpass and "vocal" sounding filter effects.

https://bomshankamachin.es/plugins/plasticityFilter

GalactiX

GalactiX 2.0, a free virtual synthesizer based on the old GalactiX plugin by Smartelectronix.
 The free version of GalactiX 2.0 is fully functional, except for DAW automation support (not available) and the inability to save user banks. 

https://www.soundmodeler.com/files/galactix.php

Sphere reverb

Sphere is an algorithmic reverb plugin based on a modified Schroeder reverberator model.
The three main controls are used to adjust the reverb’s early reflections, damping, and stereo width properties. Furthermore, the user can control the pre-delay time (up to 250 ms), feedback amount, and the cutoff frequency of the built-in low-pass filter. 

https://www.sonicbits.com/sphere.html

TapeCassette2

Tape Cassette 2 is an audio plugin that emulates the warmth, noise and character of old tape cassettes. Following up from our well received Tape Cassette 1, we've updated the plugin with a sleek interface and more changes under the hood too.

Along with a brand new selectable Type 1 Cassette Impulse Response (IR), we've improved the saturation algorithm, wow & flutter engine and implemented real sampled tape noise, all which results in a wonderfully warm and more accurate vintage sound. In addition to this you now have two VU meters to monitor your audio as well as selectable oversampling. Specifics are listed below:

• Selectable Type 1 Cassette Impulse Response (IR)
• Dynamic saturation curve algorithm implementing hysteresis and including oversampling
• Wow & Flutter engines rebuilt to focus on smoother emulation
• Real sampled noise from a Type 1 Cassette
• Low Pass range increased down to 5kHz

https://www.caelumaudio.com/CaelumAudio/?Page=TapeCassette2

Ton-Geraet 1 (SyS TG1)

SyS TG1 features a dual-voice architecture with wave-morph sequencing, frequency modulation, and a few other interesting sound-shaping tools. SyS TG1’s main standout feature is the wave-morph sequencer which draws inspiration from the legendary SID sound chip which was used in Commodore 64 home computers. The sequencer included in SyS TG1 mimics the behavior of the SID chip’s generic wavetable sequencer but without its 8-bit limitations. The wave-morph sequencer will smoothly morph between waveform shapes as the sound is playing, resulting in a uniquely complex sound character with plenty of overtones and subtones.

SyS TG1 comes with a range of other interesting synthesis features, too. There’s the 12-bit low-pass filter inspired by the Akai S-1000 hardware sampler. A dual LFO unit is installed for handling modulation, along with per-voice DADSR envelopes. Things get even more interesting with the “Stoerstrahlung” button which emulates the unstable behavior of analog gear. As the developers at SyS Audio Research describe it, this control simulates the way in which music generated by analog instruments and sequencers would sound completely different after playing continuously for several hours. 
Another handy option for sonic manipulation comes in the form of SyS TG1’s multiple oscillator routing modes. The mixing-routine switch on the back of the GUI is used to choose between additive, subtractive, inverse subtractive, and “multiply” routing for the two voltage-controlled oscillators.

http://sys.efope.de/tonge.html

Fury-800

Fury-800, a freeware emulation of the Korg Poly-800.
Its digitally controlled oscillators, noisy paraphonic filter, and the even more noisy pseudo-stereo chorus effect, all add up to create these wonderfully lo-fi, unstable sounds that almost sound as if they were captured from a VHS tape. Add some dusty plate reverb to the Poly-800’s output, and you’re in 80s synthwave heaven.You get all the synth engine features of the original and a few smart add-on options like the “God Mode” for full polyphony and 64 voices of polyphony with full velocity support.
http://music.fullbucket.de/fury800.html