Users enter the date, time and place they were born to receive an astrological chart and daily horoscopes that they can compare to those of their friends.
[2] Founder and CEO Banu Guler came up with the idea for the app after she gifted a friend's child an astrological chart that became a surprise hit at the baby shower.
[3] In 2019, Co–Star raised a $5.2 million seed round from Maveron, Aspect, and 14W, following a $750,000 pre-seed from Female Founders Fund in early 2018.
[8] Co–Star's algorithm maps human-written snippets of text to planetary movements to display personalized content for each user.
[5] That content has been called “slightly robotic,”[9] “wildly beautiful,”[5] “truly insane,"[10] “brutally honest,”[8] and compared to “a free therapy session.”[11] In July 2023, Co–Star released an in-app service called The Void that allows users to ask open-ended questions and receive answers informed by Co–Star's astrological database.