In the last decade ground-based gamma-ray telescope arrays (H.E.S.S., MAGIC, VERITAS) and the Fermi-LAT space gamma-ray telescope have given us for the first time detailed images and spectra of the high-energy universe. Currently the gamma-ray community is starting to build the next-generation ground-based gamma-ray telescope array, CTA, which will be operated as an open observatory.

Gammapy is a new open-source Python package for gamma-ray astronomy data analysis and simulation. It is built on the scientific Python stack (Numpy, Scipy, matplotlib, scikit-image) as well as other open-source astronomy Python packages (mainly Astropy, but also e.g. Sherpa, gammafit and photutils). We will present an overview of the Gammapy package and present example analyses of the real and simulated gamma-ray sky.