comparative

Calculate Synastry

Calculate a synastry chart (comparison between two subjects).

🤖 AI-optimized output available — add format=llm to reduce payload ~65%.

post/comparative/synastry

Request

  • Base URL: https://api.openephemeris.com
  • URL: https://api.openephemeris.com/comparative/synastry
  • Auth: one of:
    • HTTP bearer
    • API key in header X-OpenEphemeris-API-Key
    • API key in header X-API-Key
    • API key in header X-Service-Key

Query parameters

formatstring

Request body

include_visualboolean

If true, a full visual SVG or PNG output will be rendered and returned alongside the chart data. Note: Visuals incur a +2 credit surcharge.

Example request

{
  "subject_a": {
    "birth_datetime": {
      "iso": "1990-06-15T14:30:00"
    },
    "birth_location": {
      "latitude": {
        "decimal": 40.7128
      },
      "longitude": {
        "decimal": -74.006
      },
      "timezone": {
        "iana_name": "America/New_York"
      }
    },
    "name": "Alice"
  },
  "subject_b": {
    "birth_datetime": {
      "iso": "1992-02-10T09:15:00"
    },
    "birth_location": {
      "latitude": {
        "decimal": 34.0522
      },
      "longitude": {
        "decimal": -118.2437
      },
      "timezone": {
        "iana_name": "America/Los_Angeles"
      }
    },
    "name": "Bob"
  }
}

Response

Successful Response

Example response

{
  "chart_a": {
    "calculation_metadata": {
      "technique_id": "natal",
      "technique_label": "Composite (Davison)",
      "technique_method": "davidson",
      "technique_version": "v1"
    }
  },
  "chart_b": {
    "calculation_metadata": {
      "technique_id": "natal",
      "technique_label": "Composite (Davison)",
      "technique_method": "davidson",
      "technique_version": "v1"
    }
  }
}

Changes

No recorded changes to this operation across all 1 revision of this API.