Gammapy, a prototype for the Cherenkov Telescope Array (CTA) Science Tools, is a community-developed, open source Python package built on Numpy, Scipy and Astropy using open FITS based data formats. It provides a framework for gamma-ray data reduction and subsequent modeling and fitting to build high level science products like flux maps, spectra and light curves. In addition to methods used in traditional Cherenkov astronomy, it allows the user to do a simultaneous 3D likelihood fitting for spectra and morphology. Moreover, it enables joint likelihood analysis between different datasets, thus providing a simple platform for combined multi-instrument analysis. It has been successfully used to analyse data simultaneously from the four operational IACTs (H.E.S.S., MAGIC, VERITAS and FACT) and the Fermi-LAT, and has been shown to well reproduce results obtained with classical proprietary tools on the first H.E.S.S. DL3 data release. It was also used in the last CTA data challenge to characterise the instrument performance.
In this contribution, we present an overview of the package, the current status and the development goals, and show a few analysis examples using some open H.E.S.S. and simulated CTA data.