The Fermi surface is an important tool for understanding the electronic, optical, and magnetic properties of metals and doped semiconductors (Dugdale, 2016). It defines the surface in reciprocal space that divides unoccupied and occupied states at zero temperature. The topology of the Fermi surface impacts a variety of quantum phenomena including superconductivity, topological insulation, and ferromagnetism, and it can be used to predict the complex behaviour of systems without requiring more detailed computations. For example: (i) large nested Fermi sheets are a characteristic of charge density ordering (Lomer, 1962); (ii) the size and position of Fermi pockets are indicators of high-performance thermoelectrics (Park et al., 2020); and (iii) the average group velocities across the Fermi surface control the sensitivity of materials for dark matter detection (Inzani et al., 2021). IFermi is a Python library for the generation, analysis, and visualisation of Fermi surfaces that can facilitate sophisticated analyses of Fermi surface properties. * equal contribution † equal contribution Ganose et al., (2021). IFermi: A python library for Fermi surface generation and analysis.