Astro Timing API: moon, panchang and planet data

Quick start

No key, no sign-up. Sky endpoints use GET; chart, yogas and dasha use POST with JSON birth inputs. All return JSON with open CORS. These API calls are server-side; the website calculator runs locally instead.

curl

curl "https://whenstar.com/api/v1/today?city=Mumbai"

JavaScript, with our tiny client

One ES module, no dependencies, about 2 KB: /sdk/astro-timing.js.

import { AstroTiming } from "https://whenstar.com/sdk/astro-timing.js";

const at = new AstroTiming();
const today = await at.today({ city: "Mumbai" });
console.log(today.panchang.tithi, today.moon.phase);

const days = await at.bestDays({ goal: "launch", from: "2026-11-01", to: "2026-11-30" });
console.log(days.days[0]);

Or plain fetch

const r = await fetch("https://whenstar.com/api/v1/lunations?year=2027");
const { lunations } = await r.json();

Endpoints

The full machine-readable description is the OpenAPI 3.1 document at /openapi.json.

What the fields mean

illumination

Fraction of the Moon’s disc that is lit, from 0 (new) to 1 (full).

phase / angle

How far the Moon is ahead of the Sun, in degrees. 0 is new moon, 90 first quarter, 180 full.

tithi

The lunar day, 1 to 30. Each one is 12 degrees of that angle. 1–15 are the waxing half (Shukla), 16–30 the waning half (Krishna).

nakshatra

Which of the 27 lunar mansions the Moon is in, measured in the sidereal (Vedic) zodiac. pada is the quarter, 1–4.

tropical / sidereal

The two zodiacs. Tropical (Western) is tied to the seasons; sidereal (Vedic) to the stars, about 24 degrees behind. We use the Lahiri offset.

rahuKaal

One eighth of the daylight hours, a different eighth for each weekday, traditionally avoided for new starts. Start and end are UTC instants; convert with place.tz.

retrograde

True when the planet appears to move backwards against the stars as seen from Earth.

score (best-days)

The sum of the listed factor points. It is an editorial weighting we publish, not a personal muhurta or a forecast.

attribution

Every response includes the credit to show next to the data, with its link.

All times are UTC ISO 8601 strings. Dates without a time (YYYY-MM-DD) are civil dates in the place's time zone for panchang, and UTC for best-days. Supported years run 1900 to 2100. Errors come back as HTTP 400 with {"error": "…"} saying which parameter to fix.

Attribution and fair use

The API is free. The one condition: wherever you show our data, show a visible link to Astro Timing (the text and URL are in every response under attribution). Data is licensed CC BY 4.0.

Rate limits are fair use for now: cache what you can, and don't poll faster than the cache times above. Responses are cached at the edge, so repeated identical requests are cheap for both of us. API keys come with the public launch; nothing you build now will need rewriting beyond adding a key header.

These endpoints calculate where things are in the sky and what the traditional calendars say. They don't predict events, and no score here is a promise.

Want a widget instead of raw data? See the embeddable widgets. How the numbers are made: methodology.