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Free astrology API

Two JSON endpoints and a set of open data files. Positions are apparent geocentric longitudes on the tropical zodiac, computed with Astronomy Engine and checked against NASA JPL Horizons. The full description is in OpenAPI 3.1.

GET /api/positions

Sign, degree, speed and retrograde flag for the Sun, Moon, Mercury through Pluto, the mean North Node and mean Black Moon Lilith at any instant from 1800 to 2200.

Parameter t: an ISO 8601 UTC time such as 2026-01-01T00:00Z. Leave it out for now.

curl "https://natalchartlab.com/api/positions?t=2026-01-01T00:00Z"

{
  "time": "2026-01-01T00:00:00.000Z",
  "zodiac": "tropical",
  "frame": "apparent geocentric, true ecliptic of date",
  "positions": [
    {
      "body": "sun",
      "name": "Sun",
      "longitude": 280.56858,
      "sign": "Capricorn",
      "degree": "10°34′",
      "speed_deg_per_day": 1.01888,
      "retrograde": false
    },
    {
      "body": "moon",
      "name": "Moon",
      "longitude": 66.7167,
      "sign": "Gemini",
      "degree": "6°43′",
      "speed_deg_per_day": 14.98629,
      "retrograde": false
    },
    "…"
  ]
}

Try it.

GET /api/sky

The sky right now in one call: all positions, the Moon’s sign, phase, illumination and next sign change, void-of-course windows for the next seven days, the next New and Full Moon, and each planet’s retrograde or shadow status with dates.

const sky = await fetch('https://natalchartlab.com/api/sky').then(r => r.json());
console.log(sky.moon.sign, sky.moon.phase, sky.retrogrades.filter(p => p.status === 'retrograde'));

Try it. Responses are cached for up to 15 minutes.

Data files

The retrograde, Moon phase and eclipse tables are also on Zenodo with DOIs, and on Kaggle and Hugging Face. They are CC BY 4.0.

No code?

Use the free widgets: copy one line of HTML to show the Moon phase, Mercury retrograde status or zodiac season on your site.