Paulstretch

This is a program for stretching the audio. It is suitable only for extreme sound stretching of the audio (like 50x) and for applying special effects by "spectral smoothing" the sounds. It can transform any sound/music to a texture. The program is Open-Source and it's released under the version 2 of the General Public License. You can download the source code for Linux or the Windows binaries.

Please note that this is suitable only for extreme time stretching (e.g. if have a melody of 3 minutes and you want to listen it in 3 hours). If you want "less extreme" time stretching, you can use a program which contains the SoundTouch library.

http://hypermammut.sourceforge.net/paulstretch/

bSerrano VESTA

Vesta: Filter Fx

3 layers filtering
Each layer can be LP, HP, BP, Off, Bypass
Each layer got it own curve response that act like "spread / separation"
Layers audio routing: Parallel, serial or both.
1 LFO host syncable.
1 step controler
1 envelope follower
Stereo balance for each layer.

http://bserrano.free.fr/FX_Vesta.html 

Sound Out of the Box

XTrack EQ32

XTrack EQ32 is a VST / VST3 audio effect plugin which provides an equalizer 32 bands with a low CPU usage.
Whereas most of equalizers support only stereo control, XTrack EQ32 gives you the possibility to control a Mono, a Stereo, a LRS, a Quatro and an 8.0 Music system.
Equalization presets can be saved in a specific file in XML format. These presets are editable and can be loaded easily by the plugin via its user interface.
XTrack EQ32 has also a vumeter for input and output signal.  http://www.soundoutthebox.com/xtrack_eq32_product.php

Solcito Música

Sintetizadores virtuales

Arido 1.0 is an additive synthesizer which includes a polyphonic driver to generate greater variety of timbres.
SuperSonico 2.0 is a virtual analog synthesizer with a small additive section. 
It has a single oscillator with a generator of harmonics. The Sub-Oscillator includes an option that generates a single low octave that is repeated along the keyboard.
...
SuperTron (Dance Filter), VintagerToy (Fx), EmulTuition (FM)...
http://solcitomusica.blogspot.com.ar/p/virtuales.html

OCD DSP

Virtue is an advanced compressor unit designed for one thing, ultimate control. With this compressor look no further. Profiled compressor envelopes (FET,OPTO,VCA etc.) Internal Sidechain Filters, extreme values for creative distortion, revolutionary one of a kind fader controllers for improved accuracy & ergonomics with mouse or trackball and many more.
OCS is a saturation unit inspired by the analogue behavior. It can be used as a console saturation unit but it can have a more sporadic aproach aswell.
http://ocddsp.blogspot.fr/

LFX-1310 is a Free plug-in multi-effector including 24 types of algorithm and 3 serial slots. This freeware is the stand-alone version of Effecting Module of Ravity-S & Ravity-R. Every algorithm realizes the very effect you have on your mind, and is fully optimized for low CPU load.

http://www.luxonix.com/lfx.html

de la Mancha TRUC live multieffect

truc is a multi-effect VST plug-in, with 4 banks of effects controlled by the movement of 2 pucks. The top puck controls the level of each effect bank, the bottom puck modulates any 4 of 13 parameters within the effect banks. This allows continuous morphing of the sound by moving the pucks to vary the impact of each effect bank.
As well as manually controlling each puck (either by mouse or midi controller) you can lock the pucks together and/or set them to move automatically, either randomly or by a configurable LFO, all in sync with your project tempo.
 
https://delamanchavst.wordpress.com/2013/10/29/the-original-truc-back-for-download/

de la Mancha GTA compressor

 GTA is a vintage style ‘character’ compressor, designed like its muscle car name-sake for brute power, pure speed and to make a loud noise. It is stripped down for ease of use and has a unique vintage colouring on top.
GTA is a peak compressor featuring super-fast attack and release times and has a wide range of threshold, ratio and output boost as well as a  wet/dry mix for NY compression. The metering covers input, output and gain reduction, showing both real-time and peak levels.


https://delamanchavst.wordpress.com/2013/10/31/gta-compressor-now-available-to-download/

2tone Firebird

Firebird is not just another subtractive synthesizer, it uses a unique synthesis architecture to deliver next-generation sounds. Its innovative user interface provides you with the tools to create impressive sounds with a minimal amount of effort. Featuring an impressive selection of 437 build-in sounds, representing both highly sought-after VA sounds, as well as sounds more specific to Firebird and characterized by its Harmonic Content Morphing synthesis, breathing both life and dynamics into the sounds.

http://www.tone2.com/html/firebird_vsti_vst_synthesizer_1.html