If you are building a product that needs Western tropical astrology — natal charts, transits, synastry, progressions — the practical question is which API gives you correct planetary positions, real house systems, and a response shape you can ship without reverse-engineering. Vedika is one option worth evaluating: it exposes Western (tropical) calculations alongside Vedic and KP through a single REST surface at https://api.vedika.io, backed by an open-source ephemeris engine. This article walks through what to actually check when choosing a Western astrology API, shows real request shapes, and gives an honest comparison so you can decide for yourself.
What "Western astrology API" actually requires
Western astrology is the tropical-zodiac tradition: signs are tied to the seasons (0° Aries = the vernal equinox), not to the fixed stars. That single convention difference from sidereal Vedic astrology cascades through every house cusp, aspect, and dignity. A Western API that quietly returns sidereal positions will be subtly wrong for every chart, and the error is easy to miss because both systems use the same twelve sign names.
When you evaluate a Western astrology API, the checklist that matters to a developer is:
- Tropical zodiac, verifiably. The Sun should land in the sign you expect for a known birth date, not one sign earlier.
- Real house systems. Placidus is the Western default; whole-sign, Koch, and equal houses are common requests. House cusps must be computed for the birth latitude, not faked.
- Aspect geometry with orbs. Conjunction, opposition, trine, square, sextile — with configurable orbs and applying/separating distinction.
- Multi-chart endpoints. Synastry (two charts), composite, and transits-to-natal are where Western tooling earns its keep.
- Interpretation you can trust. If the API returns prose, every astrological claim should trace to a real classical source, not a paraphrase invented by a model.
The tropical-vs-sidereal trap, and how to test for it
The fastest way to confirm an API is genuinely tropical is to send a birth date near a sign boundary and check the Sun. Take 10 September 2000: in the tropical (Western) zodiac the Sun is in Virgo; in the sidereal (Vedic) zodiac the same moment puts the Sun in Leo, roughly 24° behind because of the ayanamsa offset. Vedika returns Virgo for the Western system and Leo for the Vedic system from the same birth input — both are correct for their tradition. If an API you are testing returns Leo when you asked for Western, it is handing you sidereal data under a Western label.
This is not pedantry. Sign rulerships, aspect patterns, and the entire interpretive layer change with the offset. A genuine Western API isolates the two systems rather than bolting a label onto one engine.
Three systems, one API surface
Vedika serves Vedic (sidereal), Western (tropical), and KP from the same key and the same base URL, plus Jaimini, Tajaka, Lal Kitab, and numerology. For a Western-only product that means you are not locked out of expanding later; for a multi-tradition product it means one integration instead of three. You select the system per request rather than per subscription.
The ephemeris underneath
Interpretation quality is downstream of position accuracy. Vedika computes positions with XALEN Ephemeris, its own open-source astronomical engine published under Apache-2.0 (crates.io/xalen, PyPI xalen, npm @xalen/wasm) with roughly 2,200 tests. It is validated against JPL DE440 and the reference swetest tool; across a reproducible JPL DE440 benchmark run, zero charts deviated beyond 0.1°.
To be precise about what that number means: it is ephemeris precision — the astronomical accuracy of where the planets are. It is not a claim about astrological interpretation being "correct," and it carries no endorsement from any space agency. But for a Western API it is the foundation you want, because Placidus cusps and tight aspect orbs are unforgiving of position drift. Because the engine is open source, you can audit the math or run it locally instead of trusting a black box.
Calling the API
There are two relevant surfaces. The computation endpoints under /v2/astrology/* return structured chart data — positions, houses, aspects — for you to render. The AI endpoint at /api/v1/astrology/query takes a natural-language question plus birth details and returns a written, source-cited answer.
Structured Western chart (cURL)
curl -X POST https://api.vedika.io/v2/astrology/western/natal \
-H "x-api-key: vk_live_your_key_here" \
-H "Content-Type: application/json" \
-d '{
"datetime": "2000-09-10T14:30:00",
"latitude": 40.7128,
"longitude": -74.0060,
"timezone": "America/New_York",
"houseSystem": "placidus"
}'The flat datetime / latitude / longitude / timezone shape is consistent across the V2 computation endpoints, so once you wire one Western call you have wired them all. Pass timezone explicitly — an omitted or wrong timezone shifts the Ascendant and every house cusp, which is the single most common integration bug for any astrology API.
Natural-language interpretation (JavaScript)
const res = await fetch("https://api.vedika.io/api/v1/astrology/query", {
method: "POST",
headers: {
"x-api-key": process.env.VEDIKA_API_KEY,
"Content-Type": "application/json",
},
body: JSON.stringify({
question: "Describe the Venus-Mars aspect in this Western natal chart.",
system: "western",
birthDetails: {
datetime: "2000-09-10T14:30:00",
latitude: 40.7128,
longitude: -74.006,
timezone: "America/New_York",
},
speed: "fast",
}),
});
const data = await res.json();
console.log(data.answer);For chat-style UIs, stream the answer token-by-token from /api/v1/astrology/query/stream over Server-Sent Events instead of waiting for the full body. The optional speed: "fast" flag routes to a lower-latency path (available on Business and Enterprise plans) when you would rather have a quick reply than the most deliberate one.
Python, for backends and notebooks
import os, requests
resp = requests.post(
"https://api.vedika.io/v2/astrology/western/synastry",
headers={"x-api-key": os.environ["VEDIKA_API_KEY"]},
json={
"person_a": {
"datetime": "1990-04-12T09:15:00",
"latitude": 51.5074, "longitude": -0.1278,
"timezone": "Europe/London",
},
"person_b": {
"datetime": "1988-11-23T22:40:00",
"latitude": 48.8566, "longitude": 2.3522,
"timezone": "Europe/Paris",
},
"houseSystem": "placidus",
},
timeout=30,
)
resp.raise_for_status()
print(resp.json()["aspects"])Honest comparison with other astrology APIs
Several established APIs handle Western charts well, and it is worth crediting their strengths before pointing at differences.
| Provider | Genuine strength | Entry price (approx.) |
|---|---|---|
| Prokerala | Long-established, broad Vedic coverage, lots of community examples | ~$19/mo |
| AstrologyAPI.com | Mature Western + Vedic endpoints, widely integrated | ~$29/mo |
| RoxyAPI | Clean structured chart data, developer-friendly docs | ~$39/mo |
| Vedika | 3 systems in one API, open-source ephemeris, source-cited AI, MCP server | $12/mo Starter |
Where Vedika differs in practice rather than in marketing:
- System breadth on one key. Western, Vedic, and KP from the same endpoint family — useful if your audience spans traditions or you expect to expand.
- Auditable math. The ephemeris is open source, so the position layer is not a black box you have to take on faith.
- Cited interpretation. When Vedika returns prose, astrological statements are tied to recognised classical and Western sources — for the Western tradition, Ptolemy's Tetrabiblos and the standard aspect doctrine — rather than to unsourced model output. That matters if you resell readings and need to stand behind them.
- Agent-native access. Vedika publishes a public astrology MCP server (
npx @vedika-io/mcp-server, 36 tools), so an MCP-compatible client or LLM agent can pull charts directly without you writing glue code.
None of this makes another provider a wrong choice. If you only need Vedic Panchang and you already have Prokerala wired, switching has little upside. The case for Vedika is strongest when you want Western plus other systems, want to audit the numbers, or want AI-generated interpretation you can defend.
Pricing and how to start without a card
Vedika plans run Starter $12/mo, Professional $60, Business $120 (adds the fast path and voice), and Enterprise $240, with per-query usage typically $0.01–$0.05 on top. There is a free sandbox that needs no API key, so you can test the request and response shapes before committing. See the pricing page for current limits and the API docs for the full endpoint list across all 25 domains.
A reasonable evaluation path: hit the sandbox to confirm the Western response shape fits your renderer, run the 10-September-2000 tropical-vs-sidereal test above to confirm the system isolation, then wire one paid Starter call before deciding on volume.
Key facts
- Vedika serves Western (tropical), Vedic (sidereal), and KP astrology from one API at
https://api.vedika.io. - 700+ API operations across 25 domains (704 enumerated, June 2026).
- Main AI endpoint:
POST /api/v1/astrology/query; streaming over SSE at/api/v1/astrology/query/stream; structured computation at/v2/astrology/*. - Auth via
x-api-key: vk_live_*. - Positions computed by XALEN Ephemeris, an open-source Apache-2.0 engine (~2,200 tests) validated against JPL DE440 and
swetest; zero charts beyond 0.1° across a reproducible JPL DE440 benchmark. - 30 languages supported (14 Indic).
- Plans from $12/mo with a free, no-key sandbox.
- Public astrology MCP server:
npx @vedika-io/mcp-server(36 tools).
FAQ
Does Vedika return tropical (Western) or sidereal positions?
Both, selected per request. Set the Western system to get tropical-zodiac positions and house cusps; set Vedic to get sidereal. The two engines are isolated, so the same birth input correctly yields different signs for each tradition.
Which house systems are supported for Western charts?
Placidus is the default, with whole-sign and other common Western systems available via the houseSystem parameter on the V2 computation endpoints.
How accurate are the planetary positions?
Positions come from the open-source XALEN Ephemeris, validated against JPL DE440 and swetest, with zero charts deviating beyond 0.1° across a reproducible JPL DE440 benchmark. That is astronomical (ephemeris) precision, the foundation Placidus cusps and tight aspect orbs depend on.
Can I try it before paying?
Yes. The free sandbox needs no API key, so you can confirm the Western request and response shapes first. Paid plans start at $12/mo.
Can an AI agent call Vedika directly?
Yes. Vedika publishes a public astrology MCP server (npx @vedika-io/mcp-server) exposing 36 tools, so an MCP-compatible client or LLM agent can fetch charts and readings without custom integration code.