The Cycles API
Send a time series, or name one you stored, and get its cycles back: dominant cycles, cyclic RSI, phase and consensus, projections. A key from your account, a header on every call, and a price per call. No membership required.
What it is
The same routines that run behind the newsletter and the analyzer, as REST endpoints. You bring the data; the API measures the cycles in it.
Every analysis route takes the values in the body of the call: cycle scan and explorer, dominant cycle, DSP filters (detrend, smooth, cyclic RSI), turning points, the cycle consensus. One call, one answer.
Store a dataset with your key and name it in later calls with ?datasetid=NAME; the server loads it inside the analysis call. Datasets you uploaded in the app and your streams work the same way.
Push bars from TradingView alerts, NinjaTrader or your own scripts into your feed and analyse the stream like any dataset. Stream updates are never charged and never count toward a cap.
Market data from our providers is not part of any plan. Where a project needs it by key, the feature MarketDataAccess is granted on request for that account; everything above works without it.
Plans
0 EUR a month
Sign in at app.cycles.org, open Account → API and activate the API as Guest. Analysis of your own data, three stored datasets, the consensus calculation, 2,000 key calls a month. Streaming as your membership allows it. No payment method, no time limit.
Activate in the FSC app5 EUR a month + <unit price> per call
A MarketZeitgeist account, a payment method, a key. Every endpoint group, safety caps per second and per minute only, no daily or monthly limit, 50 stored datasets of up to 50,000 bars, 50 live streams. Billed monthly: the base fee plus the calls of the month. Cancel at the end of any month.
Book on your account pageOn request
Fixed tiers with hourly and daily allowances for interactive work and for scripted runs over many symbols, and a developer tier with safety caps only. Set up on your account and invoiced; market data by key where the project needs it. Larger programmes and the AI tooling come with Cycles IQ.
Write to usLimits
Rates are calls per second / per minute / per hour / per day for the endpoint group. "No cap" means the period has no limit in that plan. A call above a rate is answered with an error and a retry time and is not charged.
| Endpoint group | Guest | API usage |
|---|---|---|
| Cycle analysisscan, explorer, dominant cycle, projections | 1 / 10 / 60 / 200 | 10 / 300 / no cap / no cap |
| DSP filtersdetrend, smoothing, cyclic RSI | 2 / 20 / 120 / 400 | 20 / 600 / no cap / no cap |
| Cycle consensuscalculation on your data | 1 / 5 / 30 / 100 | 10 / 300 / no cap / no cap |
| Stored datasetsstore, append, read, list, delete | 2 / 20 / 100 / 300 | 20 / 600 / no cap / no cap |
| Stream updatesrate of submissions | as your FSC membership allows | 250 / 3000 / no cap / no cap |
| Datasets stored with a key | 3, up to 5,000 bars each | 50, up to 50,000 bars each |
| Live streams you may keep | 3 from the Analyst level of the membership, none for Basic | 50 |
| Stream updates a day | 300 per stream | 300 per stream |
| Calls a month | 2,000 key calls (stream updates not counted) | no cap; every call is billed |
With the market-data feature granted, these groups apply as well (Guest / API usage): market data 2 / 30 / 300 / 1000 and 20 / 600 / no cap / no cap; symbol search 2 / 30 / 200 / 500 and 20 / 600 / no cap / no cap; market analyses of a symbol on the server 1 / 10 / 60 / 200 and 10 / 300 / no cap / no cap; dataset clustering 1 / 10 / 60 / 200 and 10 / 300 / no cap / no cap. The numbers are the tier matrix of 25 September 2026 and are reviewed against real use.
What the API answers: 401 is a missing or expired key. 403 with a message means the route is not part of your plan or needs a feature; waiting does not help, the message says what to do. 429 with Retry-After is a rate limit; 429 with a quota message is the Guest monthly cap.
Keys and documentation
Sign in to app.marketzeitgeist.com (FSC members: app.cycles.org), open Account → API and create a key. The full key is shown once. Send it in the X-API-Key header, or as Authorization: Bearer. The same page shows your limits and the calls of the month, per group.
The live reference with a quick start: api.cycle.tools/apidocs. The interactive specification, where you can run a call against your key: api.cycle.tools/specs. The API answers at api.marketzeitgeist.com and, for existing integrations, at api.cycle.tools.
Members of the Foundation for the Study of Cycles find a promotion code on the API page of app.cycles.org. Entered at checkout of the API usage plan on a MarketZeitgeist account, it reduces the price for members. The code changes from time to time; the page always shows the current one.
Terms
Use of the API is governed by the Terms of Service; MarketZeitgeist operates the API, the Foundation for the Study of Cycles grants the Guest access to its members under the same terms. Results are measurements and projections, not investment advice. Questions about a plan, the market-data feature or an integration: one e-mail.