Grav3D, a GUI-based Matlab code developed to determine the three-dimensional depth structure of a density interface. The algorithm used performs iteratively in the frequency-domain based on a relationship between the Fourier transforms of the gravity data and the sum of the Fourier transforms of the powers of the depth to the interface. In this context, the proposed code is time-efficient in computations, and thus, it is capable when handling large arrays of data. The GUI-enabled interactive control functions of the code enable the user with easy control in setting the parameters for the inversion strategy prior the operation, and also allows optional choice for displaying and recording of the outputs data without requiring coding expertise.