Ziwei Doushu casts a complete Zi Wei Dou Shu chart, the twelve-palace Purple Star astrology chart, from a birth date, birth double-hour, and gender, and shows you the whole board instead of a single fortune line. Enter the details and the engine places the fourteen major stars and supporting stars across the twelve palaces, marks each star's brightness on a seven-tier scale, and layers the Four Transformations for the natal chart, the current decade, and the current year, including flying-star self-transformations. Births near an hour boundary stay accurate because true solar time correction combines birthplace longitude with the equation of time, and the calendar edge cases are handled openly: China's 1986 to 1991 daylight-saving years, four selectable leap-month conventions, and the late Zi hour day change. Switch between natal, decade, and annual views to watch the same life read at three speeds, then look up what you are seeing. A star encyclopedia explains the fourteen major stars in each of the twelve palaces, a pattern library of more than 1,100 rules names the classic configurations on the board, and a classics library offers full-text search across public-domain source texts. Compatibility charting compares two people side by side, dark and light themes keep long study sessions comfortable, and the layout adapts to phones. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.