CycleCalcs
CycleCalcs publishes a read-only positional-astronomy engine as both a REST API and a hosted MCP server over the same core: sun and moon rise/set and twilight, moon phases and libration, planet positions and a visibility board, eclipses with per-observer local circumstances, seasons, apsides, lunar nodes, retrograde stations, conjunctions and angular separation, sidereal time, the equation of time, Jupiter's Galilean moons, sky quality and dark-sky windows, place lookup, and a one-call whole-sky snapshot. It returns the named answer and the numbers behind it rather than raw ephemeris, and every response states its frame, epoch, time scale and refraction model. Computed live with the MIT-licensed Astronomy Engine, arcminute class for the Sun, Moon and planets from 1700 to 2200. Twenty-nine GET endpoints, JSON/CSV/TXT, RFC 9457 problem documents, open CORS, and a free tier that needs no key, no signup and no card; paid volume tiers sell through RapidAPI. Pure astronomy — no astrology and no claims that sky events affect people or Earth.
Solid contracts, transparent operations, and an easy start — typically complete on four or five facets with one clear soft spot.
API Evangelist profiles CycleCalcs the way a machine reads it — 83 machine-readable artifacts across 30 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — CycleCalcs scores 62.4/100 (strong), with a separate agent-readiness read of 53/100 (agent native). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-08-17 · rubric v0.11.0
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How we profile CycleCalcs
Each block below is one kind of artifact we hold for CycleCalcs. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 30
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
CycleCalcs MCP Server
Hosted stateless Streamable HTTP MCP server exposing 11 astronomy tools backed by the v2 REST endpoints. Requires Bearer RapidAPI key on every call; basic plan free. Works with ...
CycleCalcs Apsides API
The Apsides API from CycleCalcs — 1 operation(s) for apsides.
CycleCalcs Attribution API
The Attribution API from CycleCalcs — 1 operation(s) for attribution.
CycleCalcs Conjunctions API
The Conjunctions API from CycleCalcs — 1 operation(s) for conjunctions.
CycleCalcs Conventions API
The Conventions API from CycleCalcs — 1 operation(s) for conventions.
CycleCalcs CycleCalcs Astronomy API API
The CycleCalcs Astronomy API API from CycleCalcs — 1 operation(s) for cyclecalcs astronomy api.
CycleCalcs Cycles API
The Cycles API from CycleCalcs — 1 operation(s) for cycles.
CycleCalcs Dark Window API
The Dark Window API from CycleCalcs — 1 operation(s) for dark window.
CycleCalcs Eclipses API
The Eclipses API from CycleCalcs — 1 operation(s) for eclipses.
CycleCalcs Enums API
The Enums API from CycleCalcs — 1 operation(s) for enums.
CycleCalcs Equation Of Time API
The Equation Of Time API from CycleCalcs — 1 operation(s) for equation of time.
CycleCalcs Jupiter Moons API
The Jupiter Moons API from CycleCalcs — 1 operation(s) for jupiter moons.
CycleCalcs Libration API
The Libration API from CycleCalcs — 1 operation(s) for libration.
CycleCalcs Moon API
The Moon API from CycleCalcs — 1 operation(s) for moon.
CycleCalcs Moon Nodes API
The Moon Nodes API from CycleCalcs — 1 operation(s) for moon nodes.
CycleCalcs Phases API
The Phases API from CycleCalcs — 1 operation(s) for phases.
CycleCalcs Places API
The Places API from CycleCalcs — 1 operation(s) for places.
CycleCalcs Planet Board API
The Planet Board API from CycleCalcs — 1 operation(s) for planet board.
CycleCalcs Planet Events API
The Planet Events API from CycleCalcs — 1 operation(s) for planet events.
CycleCalcs Positions API
The Positions API from CycleCalcs — 1 operation(s) for positions.
CycleCalcs Retrogrades API
The Retrogrades API from CycleCalcs — 1 operation(s) for retrogrades.
CycleCalcs Rise Set API
The Rise Set API from CycleCalcs — 1 operation(s) for rise set.
CycleCalcs Seasons API
The Seasons API from CycleCalcs — 1 operation(s) for seasons.
CycleCalcs Separation API
The Separation API from CycleCalcs — 1 operation(s) for separation.
CycleCalcs Sidereal Time API
The Sidereal Time API from CycleCalcs — 1 operation(s) for sidereal time.
CycleCalcs Sky Quality API
The Sky Quality API from CycleCalcs — 1 operation(s) for sky quality.
CycleCalcs Sun API
The Sun API from CycleCalcs — 1 operation(s) for sun.
CycleCalcs Time API
The Time API from CycleCalcs — 1 operation(s) for time.
CycleCalcs Today API
The Today API from CycleCalcs — 1 operation(s) for today.
CycleCalcs Twilight API
The Twilight API from CycleCalcs — 1 operation(s) for twilight.
Scroll within the panel for all 30 ·
Open Collections 31
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
API Collection
OPEN COLLECTIONCycleCalcs Astronomy Apsides API
OPEN COLLECTIONCycleCalcs Astronomy Attribution API
OPEN COLLECTIONCycleCalcs Astronomy Conjunctions API
OPEN COLLECTIONCycleCalcs Astronomy Conventions API
OPEN COLLECTIONCycleCalcs Astronomy CycleCalcs Astronomy API API
OPEN COLLECTIONCycleCalcs Astronomy Cycles API
OPEN COLLECTIONCycleCalcs Astronomy Dark Window API
OPEN COLLECTIONCycleCalcs Astronomy Eclipses API
OPEN COLLECTIONCycleCalcs Astronomy Enums API
OPEN COLLECTIONCycleCalcs Astronomy Equation Of Time API
OPEN COLLECTIONCycleCalcs Astronomy Jupiter Moons API
OPEN COLLECTIONCycleCalcs Astronomy Libration API
OPEN COLLECTIONCycleCalcs Astronomy Moon API
OPEN COLLECTIONCycleCalcs Astronomy Moon Nodes API
OPEN COLLECTIONCycleCalcs Astronomy Phases API
OPEN COLLECTIONCycleCalcs Astronomy Places API
OPEN COLLECTIONCycleCalcs Astronomy Planet Board API
OPEN COLLECTIONCycleCalcs Astronomy Planet Events API
OPEN COLLECTIONCycleCalcs Astronomy Positions API
OPEN COLLECTIONCycleCalcs Astronomy Retrogrades API
OPEN COLLECTIONCycleCalcs Astronomy Rise Set API
OPEN COLLECTIONCycleCalcs Astronomy Seasons API
OPEN COLLECTIONCycleCalcs Astronomy Separation API
OPEN COLLECTIONCycleCalcs Astronomy Sidereal Time API
OPEN COLLECTIONCycleCalcs Astronomy Sky Quality API
OPEN COLLECTIONCycleCalcs Astronomy Sun API
OPEN COLLECTIONCycleCalcs Astronomy Time API
OPEN COLLECTIONCycleCalcs Astronomy Today API
OPEN COLLECTIONCycleCalcs Astronomy Twilight API
OPEN COLLECTIONAPI Collection
OPEN COLLECTIONScroll within the panel for all 31 ·
Arazzo Workflows 3
Real integrations are rarely a single call. Arazzo describes the multi-step sequences — auth, then create, then confirm — so both a human and an agent can follow the choreography, not just the endpoints.
Multi-step API workflows described with the Arazzo specification.
Is the next eclipse visible from here
Resolve an observer, then ask the eclipse endpoint for an explicit visible-from-here answer with local contact times.
ARAZZOBuild a sun and moon calendar for a location
One ranged request for the solar day, one for daily moon state, one for the quarter instants — a month of calendar in three calls, not ninety.
ARAZZOTonight's sky for a place
Resolve a place name, take the whole-sky snapshot, then find the dark moonless observing window for the next week.
ARAZZOMCP Servers 2
Model Context Protocol servers expose these APIs directly to AI agents. We profile them because agent-native access is the fastest-growing way this provider's capabilities actually get used.
Model Context Protocol servers that expose these APIs to AI agents.
mcp
MCP SERVERPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.
Published pricing tiers and plan structures.
Cyclecalcs Plans
PLANSRate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Cyclecalcs Rate Limits
RATE LIMITSExamples 12
Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.
Example request and response payloads for these APIs.
Cyclecalcs V2 Cycles Example
EXAMPLECyclecalcs V2 Moon Example
EXAMPLECyclecalcs V2 Phases Example
EXAMPLECyclecalcs V2 Places Example
EXAMPLECyclecalcs V2 Sun Example
EXAMPLECyclecalcs V2 Today Example
EXAMPLEScroll within the panel for all 12 ·
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Resources
Every other property we hold for CycleCalcs — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 4
Portal, sign-up, and the first successful call
Documentation 2
Reference material describing how the API behaves
Agent Surfaces 4
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 11
Pagination, idempotency, versioning, errors, and events
Scroll within the panel for all 11 ·
Build 2
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 4
Status, limits, changes, and where to get help
Commercial 4
Pricing, plans, and the legal terms of use
Other 2
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/cyclecalcs · machine-readable index on apis.io
This is an independent, third-party profile of CycleCalcs, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
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