Open Ephemeris icon
Open Ephemeris icon

Open Ephemeris

REST API and MCP server using JPL DE440 data to return planetary positions, aspects, and chart structures for natal, transit, synastry, composite, return, progression, Vedic, BaZi, Human Design, and astrocartography workflows. Provides LLM-ready output and SVG charts.

In Claude charts with comprehensive capabilities and coverage.

Cost / License

  • Freemium (Pay once or Subscription)
  • Proprietary

Application type

Platforms

  • Online
  • Software as a Service (SaaS)
Human Design in chat, tap learn.
Vedic charts in your LLM or application with incredibly easy integration.
+2
Full suite of Bazi calculations.
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Open Ephemeris information

  • Developed by

    US flagSpirit River Inc.

  • Licensing

    Proprietary and Freemium product.

  • Pricing

    One time purchase ranging between $5 and $20, and / or subscription ranging between $29 and $199 per month + free version with limited functionality.

  • Alternatives

    8 alternatives listed

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  • Supported Languages

    • English
Open Ephemeris was added to AlternativeTo by JacksonM on and this page was last updated .
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What is Open Ephemeris?

Open Ephemeris provides accurate planetary positions, aspects, transits, and chart structures through a REST API and MCP server for building astrology apps and automations. It is an approved app in the ChatGPT app directory (one-click install) and a custom connector for Claude; in both, interactive charts render directly in the conversation.

The software uses NASA JPL DE440 data for 120 production endpoints with sub-arcsecond precision across 1,100 years for Sun, Moon, planets, and asteroids. It covers natal charts, transits, returns, progressions, astrocartography, synastry, composite and Davison charts, Human Design, electional timing search, Venus cycles, eclipses, Vedic sidereal charts, BaZi, and more.

The MCP server gives AI assistants 92 astrological tools (a curated 39-tool core surface by default), also usable from Cursor, Windsurf, Gemini CLI, and any MCP client. Adding a format=llm parameter to any endpoint roughly halves token cost. A free tier includes a one-time grant of 150 credits, no card required. Paid plans start at $29/month for 75,000 credits, with wallet top-ups from $5 and custom enterprise infrastructure available. One call returns a complete natal chart for one credit; other charts have varying credit costs.