Composite Chart API

The composite endpoint accepts two full natal charts and constructs a third chart from their midpoints. For each body it pairs the two longitudes and computes the midpoint along the shorter arc, doing the same for the two Ascendants and the two Midheavens, so the composite carries its own angles and house framework rather than borrowing either partner's. From those midpoint positions it assigns signs and houses and computes the complete internal aspect grid with applying and separating flags and exact orbs. The result is not a comparison of two people but a portrait of the bond itself — where the relationship's Sun, Moon, and angles land, which aspects structure it, and how its energies distribute across the houses. Each partner chart is supplied in the same shape as a standard natal chart, so you can compute the two natals first and feed them straight in.

curl -X POST https://api.astroway.info/v1/composite \
  -H "X-Api-Key: aw_live_..." \
  -H "Content-Type: application/json" \
  -d '{
  "chart1": {
    "date": "1990-05-15",
    "time": "14:30:00",
    "timezoneOffset": 3,
    "latitude": 50.45,
    "longitude": 30.52
  },
  "chart2": {
    "date": "1985-11-03",
    "time": "08:15:00",
    "timezoneOffset": 2,
    "latitude": 48.46,
    "longitude": 35.04
  }
}'

{
  "ok": true,
  "data": {
    "input": {},
    "planets": [
      {
        "name": "Sun",
        "longitude": 117.3,
        "sign": "Cancer",
        "house": 7
      }
    ],
    "houses": {
      "ascendant": 12.4,
      "mc": 280,
      "cusps": [
        "…"
      ]
    },
    "aspects": [
      {
        "planet1": "Sun",
        "planet2": "Venus",
        "type": "sextile",
        "orb": 0.6
      }
    ]
  }
}

Reach for the composite when the unit of interest is the relationship, not the individuals — a couple's-chart feature, a 'chemistry of the pair' report, or an AI flow that needs the relationship modelled as a single subject before it interprets. It complements synastry: synastry overlays one person's planets on the other's to show how they touch, while the composite collapses both into one derived chart to show what the relationship is in its own right. Use it for romantic pairings, business partnerships, or any two-party bond where a unified chart reads more cleanly than a cross-aspect grid. If you specifically want the time-space midpoint method — a real chart cast for the midpoint in time and place — use the Davison endpoint instead.

This is the midpoint composite: every position is the arithmetic midpoint of the corresponding pair, including the angles, so the chart has genuine cusps of its own. It is distinct from the Davison time-space midpoint chart, which is cast for the midpoint moment and location and lives on the separate /davison endpoint. Tropical zodiac and Swiss Ephemeris throughout.