Open Ephemeris is a production-grade MCP server that gives Claude, ChatGPT, Gemini, Cursor, and any MCP-compatible agent direct access to real astronomical data. Over 100 tools cover the full range of astrological traditions: natal chart calculation, transit and progression forecasting, synastry, astrocartography ACG lines, Human Design body graph, BaZi four pillars, eclipse windows, lunar phases, planetary hours, and fixed star positions. All positions are computed at request time from JPL DE440 — accurate to arc-second precision. No hallucinated positions. No astronomy math in your application code. Free tier available.
Tools
auth_login
auth_status
auth_logout
dev_call
dev_list_allowed
ephemeris_natal_chart
ephemeris_transits
ephemeris_moon_phase
ephemeris_next_lunar_phase
ephemeris_next_eclipse
human_design_chart
ephemeris_synastry
ephemeris_relocation
ephemeris_electional
electional_moment_analysis
electional_station_tracker
electional_aspect_search
vedic_chart
chinese_bazi
ephemeris_chart_wheel
ephemeris_bi_wheel
ephemeris_solar_return
ephemeris_lunar_return
ephemeris_planetary_return
ephemeris_progressed_chart
ephemeris_planet_position
ephemeris_house_cusps
ephemeris_composite
ephemeris_composite_midpoint
ephemeris_overlay
ephemeris_natal_transits
human_design_composite
human_design_penta
human_design_bodygraph
hd_planetary_return
hd_opposition
ephemeris_natal_batch
ephemeris_dignities
ephemeris_retrograde_status
ephemeris_midpoints
ephemeris_fixed_stars
ephemeris_hermetic_lots
ephemeris_angles_points
ephemeris_aspect_check
venus_star_points
venus_star_points_conjunctions
venus_eight_year_star
venus_phase
venus_elongations
venus_stations
acg_power_lines
acg_hits
Server Config
{
"mcpServers": {
"openephemeris": {
"command": "npx",
"args": [
"-y",
"@openephemeris/mcp-server"
],
"env": {
"OPENEPHEMERIS_API_KEY": "YOUR_API_KEY"
}
}
}
}