Fatiando a Terra (Portuguese for Slicing the Earth) is an open-source Python toolkit for modeling and inversion in geophysics. It provides an easy and flexible way to perform and implement geophysical data analysis.
I've started development of Fatiando in 2010 during my Masters degree at the Observatório Nacional, Brazil. I now use it daily for my research and teaching. Fatiando has grown and is now a community developed project, with contributors from different countries.
Fatiando was featured in the 89th Boletim SBGf (PDF in Portuguese).