GASTLI (GAS gianT modeL for Interiors) calculates the interior structure models for gas giants exoplanets. The code computes mass-radius curves, thermal evolution curves, and interior composition retrievals to fit a interior structure model to your mass, radius, age, and if available, atmospheric metallicity data. GASTLI can also plot the results, including internal and atmospheric profiles, a pressure-temperature diagram, mass-radius relations, and thermal evolution curves.