HarmonicBoost

Harmonic enhancer. 

• Polyphonic pitch tracking to boost the signal with harmonically matching content.
• Real-time synthesis of octave and interval shifts.
• Separate interval controls for left and right channel to enhance the stereo field.
• Smoothing control regulates the compromise of tracking speed and accuracy.
• Dropdown menu to compensate tracking latency and report it to the host.
• Visualizations to illustrate the boost signal.
• Supported sample rates: 44.1, 48, 88.2, 96, 176.4 and 192 kHz.

https://www.chromadsp.com/

Harmonics

HoRNet Harmonics is a wave shaper based on the Chebyshev polynomials. Its non-linear processing lets you adjust the level of harmonics added to the signal, warming it up in different ways.
The plugin provides 10 harmonics generators of which you can set the amplitude and phase, increasing or decreasing the impact of the harmonic on the input signal. The resulting sine wave equivalent shape is displayed on the right side of the GUI.

HoRNet Harmonics provides great flexibility and lets you create interesting distortion, try for instance to remove the fundamental frequency (set the first slider to zero) and create a “broken record” sound, or use one of the provided preset to explore the different possibilities offered by the plugin.

https://www.hornetplugins.com/plugins/hornet-harmonics/