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

Cynthia Micro

Cynthia Micro is a small subtractive synthesizer with minimal controls and a quirky character.

Features:

- 2 oscillators with 5 waveforms and split knobs
- FM controls for oscillator 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

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

Charlatan

Charlatan is a polyphonic, subtractive virtual analog (VA) synthesizer plugin with focus on sound quality and easy usability. It comes with a flexible, yet not overwhelming feature set which encourages artists to start tweaking instead of just relying on presets. Inspite of it's simplicity, Charlatan's architecture is flexible enough to create both classic sounds and rather experimental noises. While making no compromise about sound quality, the sound engine has been highly optimized for efficient CPU usage making Charlatan well suited as a "bread and butter" synth even in projects with a large number of plugin instances.

http://www.blaukraut.info/

T-Force Alpha Plus

Alpha Plus is a hybrid trance-gate synth.

It is the advanced version of the T-Force Alpha TS. It has all features of the Alpha TS with some more and some updated functions: new sythesis (Subtractive and additionally FM Synthesis), revised oscillators with some more functions and now with a separate noise oscillator, new Mod Envelopes and now with a new integrated Sidechain FX (e.g. for the typicyal sidechained pad sounds and/or pumping basses etc.).

http://www.vst4free.com/free_vst.php?id=1426

U.F.O. Zone Edition

U.F.O. Zone Edition is asubtractive synthesizer with 3 oscillators capable of many types of sounds.

• 3 oscillators with 36 waveforms.
• 2 SVF filters.
• 2 delay, chorus and reverb FX.
• Quick subpreset for ADSR envelope.
• Preset randomization system.
• Subpreset saving, loading (save OSC, filter or effects setting for use in different preset).
• 51 presets in 5 subcategories (atmosphere, effects, pads, instruments and synths)

http://www.vst4free.com/free_vst.php?plugin=U.F.O._Zone_Edition&id=1459