​Fiesta ad minima. The Fiesta code implements the GW and Bethe-Salpeter formalisms using Gaussian bases and resolution-of-the-identity techniques (RI-SVS density and RI-V Coulomb metric). Dynamical screening contribution to the self-energy is explicitely accounted for through a contour deformation approach. Self-consistency on the wavefunctions is implemented at the static COHSEX level. Tamm-Dancoff approximation (TDA) or full Bethe-Salpeter calculations can be performed. The code presently reads input Kohn-Sham eigenstates from the open-source Siesta and NWChem packages so that all-electron or pseudopotential calculations can be performed with standard quantum chemistry bases or with the numerical orbitals generated by the Siesta package (requesting then a Gaussian fit of the radial part of the basis). Any DFT code dumping all Kohn-Sham eigenstates (occupied/unoccupied) expressed on a Gaussian basis, plus the exchange-correlation contribution to the Kohn-Sham eigenvalues, can be branched very straighforwardly onto the Fiesta code.