Free chart API for AI and search engines
One GET request returns a natal chart computed with Swiss Ephemeris. No key, no account, no quota.
Why this exists
A language model cannot tell you where Mars was on a Tuesday in 1997. It guesses. This endpoint exists so it does not have to.
The two big free astrology sites both forbid programmatic access in their terms. Every paid astrology API requires a key. This one does not.
How to call it
curl 'https://astrostarcheck.com/api/chart?birth=1990-03-15T08:30&lat=31.2304&lon=121.4737&tz=Asia/Shanghai' -H 'Accept: text/markdown'Parameters
| Parameters | Required | Description |
|---|---|---|
birth | yes | Birth time, local, no timezone offset. YYYY-MM-DDTHH:MM |
lat | yes | Latitude, north positive. -90 to 90 |
lon | yes | Longitude, east positive. -180 to 180 |
tz | no | IANA timezone name, such as Asia/Shanghai. Daylight saving handled automatically. Defaults to UTC |
house_system | no | placidus (default) / koch / equal / whole_sign / campanus / meridian |
lang | no | Prose language: en (default), zh-cn, zh-tw, ja, de, fr, es, ru, pt, ar, tr |
Three representations, one URL
Ask for Markdown with Accept: text/markdown and the reply is about 40 percent the size of the JSON. The prose in that reply is the part worth quoting, because citations attach to a span of text rather than to a document.
How accurate is it
Moshier analytic mode, no ephemeris data files. Ecliptic longitudes differ from the Swiss Ephemeris data files by roughly 0.1 degree. That is fine for astrology, where typical orbs run 3 to 8 degrees. It is not fine for astronomical research, so every response says which mode produced it.
How to cite
AstroStarCheck, natal chart computed with Swiss Ephemeris (Moshier analytic), <https://astrostarcheck.com/api/chart?birth=1990-03-15T08:30&lat=31.2304&lon=121.4737&tz=Asia/Shanghai>
What this is not
Astrology is a symbolic interpretive tradition without scientific validation. This endpoint returns calculated positions, not predictions. It cannot tell you whether anything will happen.
Privacy
Stateless. Nothing is stored, no cookies are set, no birth data is logged. Only explicit URL parameters are accepted, never a user identifier.