SampleScience Player

The SampleScience Player is the biggest free rompler available today. This instrument plugin contains a core library of 200 playable instruments. You'll find everything from acoustic pianos to analog synthesizers drums. To limit the size of the plugin without compromising it sound quality, the library has been compressed to FLAC, a lossless audio compression codec.
The SampleScience Player's sounds are classified by categories which includes:

• Basic: Basic waveforms from vintage analog synthesizers.
• Bass: Various bass from synthesizers and electric bass.
• Brass: Tuba and saxophone.
• Chips: Arcade sound effects arranged as drum modules.
• Drums: Various electronic drum machines and acoustic drum kits.
• Keys: Acoustic, electric and electronic pianos and organs.
• Orchestra: Jeff Glatt public domain orchestral library.
• Perc: Percussive instruments, mostly acoustic.
• Sound Design: Excerpts from our commercial sample libraries.
• Strings: Acoustic string based instruments.
• Synth: Synthesizer sounds from both analog and software synthesizers.
• Vocals: Various sampled voices.
• Wind: Wind acoustic instruments.
• World: Instruments from around the world.
• 
  
• Bonus: Mastrcode Music Atmospheric Pads Vol.1: a collection of pads sampled as chords for that old school early jungle/techno feel.

http://www.samplescience.ca/2017/10/samplescience-player.html

Temper distortion

Creative Intent just announced their phase distortion plugin, Temper, is now free. (VST, VST3, AU).

Temper is a digital distortion audio plugin targeting VST, VST3, and AU for OS X and Windows. It builds upon traditional waveshaping techniques using modulated filter coefficients to produce a unique phase distortion. The primary signal processing loop is written with Faust, and compiled with JUCE for the various build targets.

https://creativeintent.co/products/temper

Mini G

Infected Sounds has announced that the previously commercially released Mini-g VST plugin synth is now free.
Mini-g is a very powerful mini synthesizer made for all kind of analogue sounds, "Mini-g" means mini analogue. This synth was made for some typical kind of sounds to genre the most powerful analogue sounds. We are proud to release this final product. Mini-g can make fat basslines such as leads, plucks and many more.

http://www.kvraudio.com/forum/viewtopic.php?f=1&t=499839

http://bryntebengal.wixsite.com/infected-sounds

hy-filter3

Free Version:

Two filter mode(SVF, Reso).
No modulation units and FX units

https://hy-plugins.com/product/hy-filter3/

Bakuage BasicComp

BasicComp is high-quality VST3 compressor plugin that is focused to compress dynamic range naturally. It is suitable for mastering, vocal track, and drum track.

https://bakuage.com/en/vst/

ITDPanner

ITDPanner is VST3 panner plugin specialized to control the pan of stereo sound source without sound quality degradation. ITDPanner never mix left channel and right channel, so it has no sound quality degradation caused by interference of sound. It is based on ITD(Interaural Time Difference)control and balance control.

https://bakuage.com/en/vst/

dr analyzer

DRAnalyzer is a VST spectrum analyzer that can analyze the dynamic range for each band. Although the normal spectrum analyzer can display only the instantaneous value of the spectrum, DRAnalyzer can display the past spectrums as a distribution. Since it is possible to see the dynamic range for each band from the distribution, compatibility with multiband compressors is outstanding. You can optionally correct the spectrum according to the human auditory characteristics, so you can see the sound as it is heard.

https://bakuage.com/en/vst/

Cynthia Micro is a small subtractive synthesizer that aims to be as juicy and fun as possible with a minimal set of controls.

2 oscillators with 5 waveforms and split knobs
FM controls to modulate oscillator 1 or 2
Low pass filter
Envelope modulation for FM, filter, and volume
Vibrato for oscillator 2 or oscillator 1+2
8 voice polyphony and legato mode
Cynthia Micro is free and open-source

https://tesselode.itch.io/cynthia-micro

ISOL8 mix monitoring tool

 ISOL8 v1.0.4 free mix monitoring tool 

Isol8 is an advanced mix monitoring tool. It divides the frequency range into 5 bands.

These 5 bands can be soloed or muted individually. This will help you to concentrate on certain frequency ranges during the mixing and mastering process.

Isol8 is originally designed to be used on the master track, but it can also be used on individual audio track busses.

 5 adjustable frequency bands
- Solo/mute function for each band individually
- Linkwitz-Riley crossover filter design
- 24/48dB/Oct filter slope
- Multiple filter channel modes (Stereo/Left/Right/Mid/Side)
- Multiple monitor modes (Stereo/Left/Right/Mid/Side)
- In-place or centered monitoring
- Adjustable output level
- Loudness dim function
- Large and easy to use GUI
- 64-bit internal processing

http://www.tb-software.com/TBProAudio/ISOL8.html