Wave-optics phenomena in gravitational lensing occur when the signal's wavelength is commensurate to the gravitational radius of the lens. Although potentially detectable in lensed gravitational waves, fast radio bursts and pulsars, accurate numerical predictions are challenging to compute. In this talk I will present recent advances on numerical methods to tackle this problem and their implementation in GLoW (Gravitational Lensing of Waves): an accurate, flexible and fast code able to to compute the amplification factor for generic lenses and impact parameters in O(1 ms) to O(10 ms).