DeepSky is an open planetarium and star atlas designed for people interested in exploring the night sky. Its web-based experience visualizes celestial objects in real time, showing the positions of stars, planets, and the Moon as they would appear from a selected location on Earth. Users can also choose dates ranging from the distant past to the far future to explore how the sky changes over time.

The platform includes catalogs of galaxies, nebulae, and star clusters, with detailed information about objects such as the Andromeda Galaxy. It presents constellations and sky traditions from cultures around the world, including Indigenous cultures, alongside three-dimensional models and realistic textures of the Moon and planets. Viewing options are intended to help users explore the sky with the naked eye, binoculars, or a telescope, including an eyepiece mode with atmospheric and landscape effects.

DeepSky also features an astronomy calendar. The project describes itself as open source and community-developed.