How Star Chart works

We use Open-Meteo's free geocoding service to turn your city name into latitude, longitude and timezone. We never store your birth details on any server.

The chart is built with the circular-natal-horoscope-js library, which computes planet positions using the tropical zodiac and the Placidus house system. It is based on a JavaScript port of widely used ephemeris math.

Your daily reading, personalized report and cheeky life-coach tip are generated by Google's Gemini 2.5 Flash model. The AI receives your chart data (signs, planets, houses, aspects) and your chosen language — never your full name or location.

Your chart, diary entries and reminders are stored only in your device's local browser storage. No account, no cloud sync, no analytics tracking. If you clear your browser history or open the app inside another app's built-in browser, the data may disappear.

Chart output is compared against independent, publicly documented references so the math is not trusted blindly:

• Swiss Ephemeris (Astrodienst) — reference planetary positions
• NASA JPL Horizons — official solar-system ephemeris data
• IAU / IERS — Earth rotation and time standards (UT1, ΔT)
• IANA Time Zone Database — historical DST & offset rules

Typical agreement with Swiss Ephemeris is within a few arc-minutes for the Sun, Moon and planets. House cusps depend on the exact birth time — one wrong minute can shift the Ascendant.

1. Date, exact time and place of birth — yours or your loved one's.
2. Real astronomical data, tropical zodiac, Placidus houses.
3. A personalized report you can keep, print, or gift.

This project is made by two: the vision, direction and content decisions on one side, the code and technical build on the other.