Magblox is the magnetic counterpart of Grablox and suits 3D modelling and inversion of magnetic data. However, Magblox is not as well developed and tested as Grablox. The inversion is based on SVD, which is very slow when the dimension of the problem (number of model elements and number of data) becomes large. Originally, Magblox was not made public but because of many requests, I decided to give it a chance. As with all the other software of mine - use at you own risk.