9 Top Astrology Apps 2022 | Horoscope.com Co-Star. Courtesy of Co-Star Astrology Society. Best for: Beginners, trend-followers, colloquialisms. This was one of the first apps to revolutionize the astrology market. With its sleek, modernist design and brutally honest notifications, Co-Star is popular because it resonates with many people. Compare your chart to any friends who have the ...