Co-Star
Co-Star Astrology · 'Co-Star: Personalized Astrology'
What it is
Co-Star, a mobile astrology app developed in 2017 in New York by Banu Guler and her team. Launched on iOS and went viral quickly. By 2024, 30 million downloads — the most successful consumer app in astrology's history. Uses NASA's JPL Horizons API for real-time transit calculation; sends daily "push notification"-style short, dry, sometimes harsh interpretations. Co-Star's language became a brand: "Today you'll probably fail at communication. We saw it coming." Gen Z and millennials' modern astrology-speech style was largely shaped by Co-Star's influence. Criticism: interpretations are sometimes hurtful, overly categorical. Their answer: users read it as "ironically serious" anyway.
Why it matters
The central app of astrology's 4th major mass boom (2017-2020). The modern astrology-speech style (#GeminiSeason humor on Twitter, identifying personality through the Sun-Moon-Rising trio) spread through Co-Star.
Themes
- mobile boom
- Gen Z
- 30M downloads
- edgy daily