This is a demo of Prodyon Enchoir – a vocal harmonizer for Windows.
Enchoir creates up to 6 voices of background vocal harmony based on chords played on a MIDI keyboard. It also features natural sounding reverb, internal 24-voice doubling with formant shifting, scooping, vibrato via aftertouch, harmony-hold function and a unique harmony-shift mode that alters choir voies based on notes played on your keyboard.
It’s currently on sale for $27. A demo version is available.