Freeware - Valhalla Space Modulator Flanger Plugin

https://valhalladsp.com/shop/modulation/valhalla-space-modulator/

Earth Shattering Kaboom. ValhallaSpaceModulator is our take on flanging. Eleven algorithms allow you to get through-zero flanging, barberpole flanging, detuning, doubling, strange echoes, reverbs, and all sorts of effects that defy description.