Charts, synastry, spirit lookups, divination casts, planetary hours, and
cross-tradition graph traversal — through a documented REST API and an MCP
server. Clean JSON. 30 req/min free tier, no credit card.
/api/stars/health answers with no key; everything else
takes an API key.
Call the real API from this page. The Health check preset
works with no key; the others expect an API key (add
-H "X-API-Key: …" once you have one). Edit any request and hit
Send.
the whole engine, behind every category
93 traditional D0–D2 systems converge at cosine 0.515–0.523 across 500 charts (511 comparable pairs), engine hypotheses excluded. Engine 2.7.0. Verified 2026-09-08.
curl, requests, fetch — any HTTP client. JSON
in, JSON out, consistent error envelopes. /api/stars/health
is open; every other route authenticates with an API key.
Natal chart, session brief, convergence hotspots, synastry, transits,
concept lookup, Rosetta translation, graph adjacency, journalling. SSE
transport, JSON-RPC 2.0, at stars.madmanwithabox.org/mcp/sse.
Practitioner tier and above.
Every endpoint returns JSON and is described in an OpenAPI spec — codegen a client in your language, or point an agent at it.
The same birth data returns the same chart, forever — so responses are cacheable, diffable, and safe to snapshot in a test suite.
A sample of the surface:
Start in 30 seconds:
# Open — no key
curl "https://stars.madmanwithabox.org/api/stars/health"
# Everything else takes an API key
curl -H "X-API-Key: $STARS_API_KEY" \
"https://stars.madmanwithabox.org/api/stars/esoteric/spirits?sign=Aries°ree=15"
Not on AWS, Google Cloud, or Azure. Chart computation runs on a dedicated server in Texas against the JPL DE440 ephemeris; the public frontend is on independent infrastructure in Germany. Your birth data reaches our machine, not a cloud maths API — and the ephemeris never leaves our server.
Requests aren't training data and aren't for sale. We don't log your API calls for analytics. The free tier is a free tier, not a data-harvesting funnel.
Explorer $0/mo · Enthusiast $12/mo · Practitioner $59/mo · Studio $199/mo. Free tier 30 req/min. No "contact sales," no enterprise pricing call.
Stars computes and documents; the application is yours. Founding developers get a permanent free account for telling us where the API is awkward, what's missing, and which endpoint you wish returned one more field.
Invite-only beta. Free tier 30 req/min, no credit card. Your data isn't the product — your subscription is.