BoltzTraP2 is a modern implementation of the smoothed Fourier interpolation algorithm for electronic bands that formed the base of the original and widely used BoltzTraP code. One of the most typical uses of BoltzTraP is the calculation of thermoelectric transport coefficients as functions of temperature and chemical potential in the rigid-band picture. However, many other features are available, including 3D plots of Fermi surfaces based on the reconstructed bands.