MidiTransposer - MidiTransposer is a VST audio plugin that converts a monophonic audio track into a polyphonic one, transposing instruments and vocals.
Serum - VST for FL Studio, Ableton Live, and many other VST supported DAWs. Heavily utilized in EDM.
Waves Abbey Road Vinyl - Waves Abbey Road Vinyl is a vintage vinyl record music effect software instrument that allows music producers and engineers to re-create the sound of vinyl on computers and other digital devices.
Surge XT - Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.
Unstable by De La Mancha - Unstable by De La Mancha is a pitch modulation effect tool packed with inspiration and creativity.
Vital - Vital is a spectral warping wavetable synthesizer with drag'n'drop modulation workflow and animated preview of the synth's inner workings where needed. Comes with many modulation sources (including audio-rate), MPE support and FX chain.