curl -X POST "https://astrologer.p.rapidapi.com/api/v5/birth-chart" \
  -H "Content-Type: application/json" \
  -H "X-RapidAPI-Key: YOUR_KEY" \
  -H "X-RapidAPI-Host: astrologer.p.rapidapi.com" \
  -d '{
    "subject": {
      "year": 1990, "month": 1, "day": 15,
      "hour": 14, "minute": 30,
      "city": "New York", "nation": "US",
      "name": "John Doe"
    }
  }'

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Why Choose This Astrology API

Arcsecond Precision

Professional-grade astronomical calculations. Accurate to arcseconds for all 63 celestial points.

Any Language via REST

Python, JavaScript, Go, Rust, Swift, Kotlin — any language that speaks HTTP.

Free Tier on RapidAPI

Start building in 2 minutes. No credit card required for the free plan.

22 House Systems + 48 Ayanamsa

Western and Vedic astrology. Placidus, Whole Sign, Koch, Lahiri, and more.

AI-Ready XML Context

Structured astrological data for Claude, GPT, and any LLM. No parsing needed.

SVG Output, 6 Themes

Scalable, accessible, CSS-stylable charts in 10+ languages.

Start Building

Astrology API Use Cases

AI / LLM Apps

Build Claude/GPT wrappers that reason about natal charts. AI Context XML built-in.

Start Building →

Mobile Apps

Add astrology to iOS/Android via REST. No Python dependency, no infrastructure.

Start Building →

SaaS Platforms

Commercial use allowed. Predictable pricing on RapidAPI. No AGPL concerns.

Start Building →

Daily Horoscope Services

Moon phases + transits + planetary positions for automated content generation.

Start Building →

Library vs API — Which One?

Criteria	Kerykeion Library	Astrologer API
Language	Python only	Any (HTTP)
License	AGPL-3.0 (copyleft)	Commercial-friendly
Closed-source use	⚠️ Restricted	✓ Allowed
Setup	Install + maintain	Zero setup
AI Context	Build your own	✓ Built-in XML
Source Code	✓ Open source	✓ Open source
Cost	Free	Free tier + paid

Ready for production? Use the API →

Pricing

Start free, scale as you grow. All plans include every endpoint.

Pro

$9/mo

5,000 requests/month

Recommended

Ultra

$18/mo

50,000 requests/month

Mega

$40/mo

1M requests/month

View Pricing on RapidAPI

For Claude Code, Cursor, Lovable & Any AI Coder

Your AI Agent Builds the App

Two paths: install the skill for agents that support it, or drop a single-line prompt into any other coding agent. Both give the agent everything it needs.

Skill-Capable Agents

Claude Code, Cursor, Windsurf, Cline, Gemini, Copilot, Goose, OpenCode, Roo.

Via skills.sh:

npx skills add g-battaglia/Astrologer-API

Or direct curl (Claude Code):

curl -fsSL https://raw.githubusercontent.com/g-battaglia/Astrologer-API/main/skills/astrologer-api/SKILL.md \
  -o ~/.claude/skills/astrologer-api.md

Full install guide

No Skill Support? Drop This Prompt

Lovable, Bolt, v0, Replit Agent, ChatGPT, Gemini — paste this in the chat and the agent fetches the full docs itself.

Use the Astrologer API to build [feature].
Full docs: https://kerykeion.net/astrologer-api/llms-full.txt
Fetch that file first, then implement.

llms.txt llms-full.txt

Developer Guides

Step-by-step tutorials for every integration pattern.

Astrology API — Complete Guide → Birth Chart API Tutorial → Build a Horoscope API Feature → Synastry & Compatibility API → Astrology API for AI / LLM → Moon Phase API Tutorial → Zodiac Sign API → How to Build an Astrology App →

View all guides

Open Source

Built in the open

Astrologer API is fully open source. Read the code, audit the calculations, contribute improvements, or fork it. Powered by the Kerykeion Python library — also open source, used in production by apps worldwide.

No lock-in. Transparent math. Community-driven.

Astrologer API Kerykeion Library

What's open

✓
API source code
FastAPI backend, tests, docs generation.
✓
Kerykeion library
Core astrology engine. AGPL-3.0.
✓
All calculation logic
Planets, houses, aspects — fully auditable.
✓
Chart rendering
SVG templates, themes, translations.

Frequently Asked Questions

What is Astrologer API?

Astrologer API is an astrology API — a REST service for astrological calculations including natal charts, synastry, transits, moon phases, SVG chart rendering, and AI-powered interpretations. Built on the Kerykeion library with arcsecond precision.

Is there a free tier?

Yes. This astrology API offers a free tier on RapidAPI for testing and prototyping. Paid plans are available for production use.

What programming languages can I use?

Any language that can make HTTP requests — Python, JavaScript/TypeScript, Go, Rust, Swift, Kotlin, Ruby, Java, C#, and more. The API uses standard REST with JSON.

Can I use this astrology API for commercial projects?

Yes. The Astrologer API is consumed as an external service rather than importing the AGPL library directly, so it can be used in closed-source and commercial applications via RapidAPI.

What's the difference between using an astrology API and the Kerykeion library?

Kerykeion is a Python library (AGPL-3.0) you install and run locally. The Astrologer API is a hosted astrology API built on Kerykeion — your app consumes it as an external service rather than importing the AGPL library directly. No Python required, no infrastructure to manage, and commercial-friendly licensing.

How accurate are the calculations?

Astrologer API delivers professional-grade calculations accurate to arcseconds for all 63 celestial points, with 22 house systems and 48 sidereal modes.

Can I integrate with Claude or GPT?

Yes. This astrology API provides AI Context XML endpoints that output structured astrological data ready for LLM prompts. Feed the response directly into Claude, GPT, or any LLM.

Does it support Vedic astrology?

Yes. This astrology API supports 48 sidereal ayanamsa modes including Lahiri, Fagan-Bradley, Krishnamurti, and a custom USER mode for arbitrary offsets, alongside 22 house systems.

Start Building With the Astrology API

Join developers building astrology apps with the Astrologer API — the astrology API designed for production.

Get Your API Key