Blog
Updates & Guides
From calculation engines to cosmic timing — lessons from building OpenEphemeris.
2026-08-19
Beyond the Ten Planets: 90 Bodies and 124 Fixed Stars
Most ephemeris work stops at the ten planets. OpenEphemeris now computes 90 bodies and 124 fixed stars — asteroids, trans-Neptunians, and Uranian points, all from NASA JPL data.
apiasteroidsfixed-starsastrologyuraniandevelopers2026-08-16
How to Choose an Astrology API
How to choose an astrology API — data source, systems covered, LLM/agent readiness, pricing, and licensing, across five options. Written by OpenEphemeris, one of them.
astrology-apicomparisondevelopersmcppricing2026-08-16
Can ChatGPT or Claude Do Astrology?
Yes for interpretation, no for the numbers underneath it. Here is what ChatGPT and Claude actually get wrong about your chart, and the two-minute fix.
aichatgptclaudeastrologyaccuracymcp2026-08-16
How to Calculate Planetary Positions (By Hand, Library, API)
Solve Kepler's equation by hand, call an ephemeris library, or make one REST request — three ways to calculate planetary positions, compared honestly.
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How Is a Human Design Chart Calculated?
The Design chart is cast 88 degrees of solar arc before birth, not 88 days. Here is the ecliptic math and gate wheel behind every Human Design chart we compute.
human-designastrologyephemerisgatesbodygraphapi2026-08-16
Swiss Ephemeris vs. JPL DE440: Which One Should Your App Use?
Swiss Ephemeris and JPL DE440 are not rival data sources — one is compressed from the other. Here is how licensing, accuracy, and setup cost actually compare.
comparisonswiss-ephemerisjpl-de440ephemerisdevelopers2026-07-27
A Timestamp Is Not a Moment: Timezone and Location Handling in Astrological Software
Why a datetime without a zone is not a moment, which parts of a chart a few hours of error destroys, which parts hide it, and the order you have to resolve place, zone, and instant in.
engineeringtimezonedatetimeapiastrologydata-quality2026-07-21
The Human Design Bodygraph, Drawn as a Full Mandala
Render the Human Design bodygraph as a full mandala — I Ching wheel, zodiac, and twin astrological house rings computed from real cusps. One API call.
human-designbodygraphmandalahousesapimcpvisualization2026-07-19
Add an Interactive Astrology Chart to Your Website
Add an interactive natal chart, synastry bi-wheel, or Human Design bodygraph to any website. Two lines of HTML, no code skills, leads included.
embedwidgetastrologyhuman-designlead-generationapi2026-07-18
Connect Any AI Agent to Verified Astronomical Data with the Open Ephemeris MCP Server
The Open Ephemeris MCP server gives Claude, ChatGPT, Gemini, and any MCP-compatible agent access to JPL DE440 planetary data. Real positions. No hallucinations. Two-minute setup.
mcpastrologyapiai-agentsclaudellm2026-07-18
Astrology for AI Agents: Why Accuracy Is the Whole Game
Building an astrology agent? The hard part is not the interpretation — it is the data. Here is why agents need a deterministic calculation layer, and how MCP provides one.
ai-agentsmcpastrologyapiaccuracydevelopers2026-07-18
OpenEphemeris Is Now Available as a Claude Connector
Add OpenEphemeris to Claude as a connector and get real planetary positions, charts, and Human Design — calculated, not guessed.
claudemcpastrologyhuman-designai-agentsconnector2026-04-23
BaZi Gets Serious: Six New Analytical Endpoints for the Four Pillars
OpenEphemeris now exposes six professional-grade BaZi analytical endpoints — Ten Gods, Luck Pillars, Annual Pillar, compatibility, element balance, and all 24 Solar Terms — each validated against canonical doctrinal sources.
chinese-astrologybaziapichangelogfour-pillars2026-04-01
The Developer's Guide to Astrology APIs
A practical guide to integrating astrological calculation into your application — what an astrology API provides, how to evaluate options, and how to make your first call.
developersastrology-apitutorialrest-apinatal-chart2026-04-01
Turn Claude into a Master Astrologer (No Code Required)
Connect OpenEphemeris to Claude in five minutes. Get a real birth chart — planetary degrees, house placements, and transits calculated from NASA JPL data, not AI guesswork.
claudemcpastrologyhow-tobeginner2026-04-01
What Is an Ephemeris? (A Practical Guide for Developers and Curious People)
An ephemeris is a table of planetary positions over time — the foundation of astrology, astronomy, and navigation. Here is what it is, how it works, and how to use one via API.
explainerephemerisastronomyastrologybeginner2026-04-01
Why AI Gets Astrology Wrong (And What Actually Fixes It)
AI assistants sound confident about astrology but frequently invent planetary positions. Here is why it happens, why it matters, and the architectural fix that eliminates it.
aiastrologyhallucinationaccuracymcp