What it is
Co-Star is a consumer astrology app launched in 2017 by Co-Star Astrology Society, a small studio based in New York. The product runs on iOS and Android, ships push notifications about daily transits, and is best known for its conversational copywriting voice — short, sharp, occasionally rude horoscope text that went viral with millennial and Gen Z users between 2018 and 2020. Co-Star has crossed 30 million installs by various press reports, monetizes via in-app purchases for compatibility readings, and is the dominant consumer astrology app by US install count alongside The Pattern and CHANI. The brand voice and minimalist black-and-white UI are the product's actual moat, not the chart calculation.
Who uses it
Co-Star's audience is the 18 to 32 year old urban consumer who learned about their rising sign from a friend and downloaded the app for the daily push notification. Roughly 70 percent of installs are women in major US, UK, and Australian cities. The typical session is 30 to 90 seconds — open the app, read the daily horoscope, occasionally check a friend's compatibility, close. Practitioners with paying clients are not Co-Star's audience. The chart calculation has shipped errors flagged by professional astrologers (incorrect house assignments at high latitudes, occasional rising-sign mistakes near sign boundaries), and house system is locked.
Headline features
- Daily push notifications with conversational horoscope text
- Friend compatibility via in-app purchase ($4.99 to $9.99 per pair)
- Minimalist black-and-white UI that became the visual reference for consumer astrology apps
- Free with optional premium add-ons
- iOS and Android, with feature parity on both platforms
- Single house system (Placidus default), no choice
- Chart calculation has documented edge-case errors at high latitudes
Headline price and 5-year cost
The app is free. In-app purchases for compatibility readings cost $4.99 to $9.99 per pair, and heavy users spend $50 to $120 a year on IAPs. Over 5 years, a casual user spends $0; a heavy compatibility-reader spends $300 to $600 total across 60 months.
Where Astrolium does it differently
Co-Star and Astrolium do not compete. The audiences barely overlap. Co-Star is a consumer push-notification app for daily horoscope reading; Astrolium is a paid practitioner workspace for working astrologers with clients. The honest summary: Co-Star is well-designed for what it does, and the team would recommend it to a friend who is not running a paid practice.
Where the gap matters is when a Co-Star user becomes serious enough to start reading for friends, then for paying clients. The app does not scale to that work. There is no roster, no intake form, no session notes, no shareable chart link the client opens in their browser, no Stripe invoicing, and no Hellenistic technique support (no profections, no Zodiacal Releasing, no time-lord stack). The 23 house systems Astrolium ships, plus 20,000 plus named asteroids and the live predictive scrubber, are aimed at the practitioner who has outgrown the daily push notification. Astrolium also supports 9 languages out of the box.
For consumer use, keep Co-Star. For a paid practice, the toolset is different.
If you are moving from Co-Star
The full comparison with other consumer apps (CHANI, The Pattern, LUNA) lives at Consumer apps vs Astrolium. For Astrolium's pricing, the Free tier, and the features hub, the links go to the working surfaces.
Start the wizard if you are crossing the line from consumer app user to working astrologer with a small practice.