The Aeolus library, written in Python, analyzes and plots climate model output using modules to work with 3D general circulation models of planetary atmospheres. The code provides various functions tailored to exoplanet research, e.g., in the context of tidally-locked exoplanets. Generic (planet-independent constants) and basic constants of the Earth atmosphere are also provided. Aeolus can store model-specific variable and coordinate names in one container, which can be passed to various functions, and can also calculate the synthetic transmission spectrum.