Natal Chart API in Python: 3 Examples with the AstroWay SDK

If you’re building astrology features in Python, you have two paths: bundle an ephemeris library and do the math locally, or call an API that already does it. This post takes the API route with AstroWay — pip install, a first natal chart, then transits and synastry — and shows where each approach makes sense.

pip install astroway
# or: uv add astroway / poetry add astroway

Grab a key at the dashboard — 10,000 credits/month free, no card. A full natal chart costs 20 credits, so the free tier covers roughly 500 charts a month.

The SDK exposes typed namespaces generated from the OpenAPI spec. chart.compute takes a BirthData model (or a plain dict) and returns the unwrapped result — no { ok, data } envelope to peel:

from astroway import Astroway, BirthData

aw = Astroway(api_key="aw_live_...")

chart = aw.chart.compute(BirthData(
    date="1990-07-14",
    time="14:30:00",
    timezone_offset=3,
    latitude=50.45,
    longitude=30.52,
))

for planet in chart.planets:
    print(f"{planet.name:10} {planet.longitude:.2f}° in {planet.sign}")

The API does not geocode — pass the latitude/longitude and the UTC offset for the birth moment yourself (a one-line lookup with geopy + timezonefinder if you only have a city name).

Transit-based features (daily insights, “Saturn is squaring your Sun”) need a second date. transits.compute takes the birth data plus a target_date:

from astroway import TransitsRequest

transits = aw.transits.compute(TransitsRequest(
    date="1990-07-14", time="14:30:00", timezone_offset=3,
    latitude=50.45, longitude=30.52,
    target_date="2027-01-01",
))

for hit in transits.aspects:
    print(f"{hit.transiting} {hit.aspect} natal {hit.natal} (orb {hit.orb:.1f}°)")

This is the real difference between a calculation API and a “horoscope text” API: you get the actual aspects, not a paragraph generated by an LLM.

synastry.compute takes two charts and returns the inter-aspect grid plus a compatibility score:

from astroway import SynastryRequest

result = aw.synastry.compute(SynastryRequest(
    chart1=BirthData(date="1990-07-14", time="14:30:00", timezone_offset=3, latitude=50.45, longitude=30.52),
    chart2=BirthData(date="1992-03-22", time="09:15:00", timezone_offset=2, latitude=48.85, longitude=2.35),
))

print(f"Compatibility: {result.score}/100")

The async client has the same surface. Retries on 429/5xx with exponential backoff are built in, and errors are a typed hierarchy:

import asyncio
from astroway import AsyncAstroway
from astroway import RateLimitError, BadRequestError

async def main():
    async with AsyncAstroway(api_key="aw_live_...") as aw:
        try:
            chart = await aw.chart.compute({
                "date": "1990-07-14", "time": "14:30:00",
                "timezoneOffset": 3, "latitude": 50.45, "longitude": 30.52,
            })
        except RateLimitError:
            ...  # back off and retry later
        except BadRequestError as e:
            print(e)  # which field failed validation

asyncio.run(main())

(Note: the BirthData model uses timezone_offset; a raw dict uses the JSON field name timezoneOffset. Both work.)

• pyswisseph — Python bindings for the Swiss Ephemeris C library. Maximum control, but you compile a C extension, ship the ephemeris data files, and implement house systems, aspects and chart logic yourself.
• kerykeion — a higher-level library on top of pyswisseph. Less boilerplate, but still a local dependency you install, version and deploy.
• AstroWay — the same Swiss Ephemeris engine (compiled to WebAssembly server side), reached over HTTP. Nothing to compile or ship; you trade a network round-trip for zero install and 722 endpoints beyond the natal chart (synastry, transits, Vedic, Human Design, AI interpretations).

Rule of thumb: a CLI tool or a notebook that runs offline → a local library. A web app, a serverless function, or anything where you don’t want to manage ephemeris files and house-system code → the API.

• Python SDK reference — full namespace list
• Pricing — credit costs per endpoint
• Birth Chart API — the natal endpoint in depth
• Best astrology APIs in 2026 — how the options compare