Pricing
What is free stays free. The paid options below add capacity, service terms, documents and widget licenses; none of them changes an answer.
On this page
Free
Every calculator and tool on the site, every widget, the API's Basic tier and the MCP server are free, and stay free. Every API tier serves the same answers (tiers), and every widget is free for any website, with no account and no key (widgets).
- The API with no key: 300 requests a minute, 2,000 an hour and 5,000 a day per network address.
- The MCP server: up to 50 tool calls a day per network address without a key.
- The widgets, with a small caption link under each card.
The values we compute are public domain under the site license for everyone, paid or not, so nothing below sells data rights. Values from third-party catalogs keep the terms listed in NOTICE.md.
Founding Member
Founding Member
$299 once
$299 until 23:59 ET Tue 27 Oct 2026 or the first 100, whichever comes first; then $499 until it closes at 23:59 ET Wed 4 Nov 2026. It is not sold again at $499 or less.
A fixed bundle for one person. The three documents arrive at purchase; the API key and widget license follow by email within 1 business day.
- One each of Moon Calendar 2027 (regenerate it until 1 Feb 2028), Your Eclipse Day 2027 (until 1 Oct 2027) and The Moon That Night, Occasion Edition (one year, for the date you pick at checkout). Each has a free preview on its own page.
- Each future Moon Calendar edition, free, sent by email while it is sold.
- A widget license for one website domain and its subdomains: the widgets without the CycleCalcs mark, in your accent color. Websites only. See a widget before and after.
- A personal API key at the Founding windows, with a 5 GB monthly transfer allowance, for the API and the MCP server.
- Email support, best effort.
Available from Wed 14 Oct 2026.
What the membership promises
- It is guaranteed for at least 5 years from purchase, and continues for as long as CycleCalcs LLC sells the Founding or Professional product after that.
- The key's rate windows and transfer allowance are never lower than at purchase.
- If we withdraw the Founding membership as a whole within those 5 years, we refund the unused months pro rata over 60 months. A dated edition that ends on schedule is not a withdrawal.
- It belongs to one person and cannot be transferred, except once to a company that person wholly owns.
- The key covers that person's own projects and client prototypes. The production backend of a product that charges its users or has more than 1,000 monthly active users needs API Annual.
- Refund within 30 days, no reason needed.
Professional
Professional
$1,000 once
For one person: freelancers and consultants.
Everything in Founding Member, plus:
- A personal API key at the Professional windows, with a 10 GB monthly transfer allowance.
- Widget licenses for three website domains.
- The event database: phases, eclipses, seasons, stations, node crossings and conjunctions from 1900 to 2100, as versioned CSV and JSON files with checksums, regenerated once a year while it is sold. It is released 31 days after purchase, after the refund window. The values stay public domain; the delivered files may not be redistributed. A free sample of all of 2027, in the same file layout, may be shared freely: one zip with every family as CSV and JSON, the checksums and a README.
The same 5-year guarantee, personal-use limit and 30-day refund as Founding Member. The documents arrive at purchase; the key and widget licenses follow by email within 1 business day.
Available from Wed 14 Oct 2026.
API Annual
For apps that call the API from a backend, prepaid by the year, for business use. Every API Annual key runs at the Mega windows and range caps today, with no monthly request meter; Growth and Scale windows are raised in writing after a load test. Each tier includes a 99.5% monthly availability commitment with service credits, MCP at the key's windows, the event database and a 12-month notice before any /v2 endpoint is retired.
Starter
$3,500 a year
About $292 a month. By card, or by invoice from CycleCalcs LLC on request.
- Mega windows, 60 GB monthly transfer allowance.
- Widget licenses for three website domains.
- Email support, best effort.
- The key and widget licenses follow by email within 1 business day of payment. The event database is released on day 15.
- By card: a full refund within 14 days if the key has made fewer than 10,000 calls.
Available from Wed 14 Oct 2026. For an invoice, email info@cyclecalcs.com.
Growth and Scale
$7,500 or $12,000 a year
About $625 or $1,000 a month. By invoice only.
- Growth: everything in Starter, 120 GB a month, five domains, and a first reply within 2 business days.
- Scale: everything in Growth, 250 GB a month and ten domains.
- Mega windows now, raised in writing to the tier's own windows after a load test. If that has not happened 90 days after signature, you may end the order for a pro-rata refund of the unused term.
Ask by email for an order form.
If you need fewer than 1,000,000 requests a month and none of the service terms, invoice or files above, Mega on RapidAPI at $15 a month sells the same windows and range caps, and is the better buy.
Enterprise
By proposal, for companies building astronomy into their own products. Every proposal says in one line why the free tier does not fit you, and what the API covers and does not cover for your use.
- Launch, $15,000 a year: everything in Scale, plus the right to proxy or resell raw /v2 and MCP access under your own brand, an incident email for any incident the status page records longer than 15 minutes, an accuracy statement for each release, and an order form, master agreement and data-processing terms. 250 GB a month, ten domains.
- Plus, $30,000 a year: Launch, plus 500 GB a month, 50 domains, two named technical contacts, a quarterly accuracy report, and your additive endpoint requests considered first.
- Partner, $100,000 a year: Plus, plus windows set by written agreement after a load test, 1,000 GB a month, and a launch-partner package. No exclusivity.
A 30-day pilot is offered within a proposal, by invoice, and is credited in full against a Growth, Scale or Enterprise invoice signed within 30 days after it ends. No refund once its key is issued. Ask for a proposal by email.
Schools, departments and planetariums
Licenses for one classroom, one department or school, and one venue, covering printed handouts of the moon calendar and the eclipse plan, get their own page in the educators section. The free lessons stay free. Until that page is up, ask by email.
The options compared
Rate windows are approximate and count only requests that reach our servers; answers served from the CDN do not count. Above its monthly transfer allowance a key is served as a caller without a key (free windows and range caps) until the UTC month ends, with a warning.
| Free | Founding Member | Professional | API Annual Starter | API Annual Growth | API Annual Scale | |
|---|---|---|---|---|---|---|
| Price | $0 | $299, then $499, once | $1,000 once | $3,500 a year | $7,500 a year | $12,000 a year |
| Use | Any, under the API terms | Personal | Personal | Business | Business | Business |
| Rate windows | ||||||
| Requests a minute | 300 | 600 | 1,200 | 2,000 | 2,000 now | 2,000 now |
| Requests an hour | 2,000 | 5,000 | 10,000 | 50,000 | 50,000 now | 50,000 now |
| Requests a day | 5,000 per address | 10,000 | 20,000 | 200,000 | 200,000 now | 200,000 now |
| Monthly transfer allowance | No key | 5 GB | 10 GB | 60 GB | 120 GB | 250 GB |
| Range caps: how much sky one request may ask for | ||||||
| Daily rows, one body | 366 | 1,830 | 3,660 | 3,660 | 3,660 | 3,660 |
| Daily rows, all bodies | 93 | 366 | 366 | 366 | 366 | 366 |
| Sub-daily grid, days | 31 | 93 | 186 | 186 | 186 | 186 |
| Events in one list | 100 | 400 | 500 | 500 | 500 | 500 |
| What else is included | ||||||
| MCP server | 50 calls a day per address | At the key's windows | At the key's windows | At the key's windows | At the key's windows | At the key's windows |
| Mark-free widget domains | None; free widgets carry a caption link | 1 | 3 | 3 | 5 | 10 |
| Documents | Free previews | 3, plus future Moon Calendar editions | 3, plus future Moon Calendar editions | Not included | Not included | Not included |
| Event database, 1900 to 2100 | Not included | Not included | From day 31 | From day 15 | Included | Included |
| Service level | None | 99.5% target, no credits | 99.5% target, no credits | 99.5% with credits | 99.5% with credits | 99.5% with credits |
| Support by email | None promised | Best effort | Best effort | Best effort | First reply within 2 business days | First reply within 2 business days |
| Term | None | At least 5 years, then while sold | At least 5 years, then while sold | 1 year, plus 30 days' grace | 1 year, renews by invoice, plus 30 days' grace | 1 year, renews by invoice, plus 30 days' grace |
| Refund | Nothing to refund | 30 days, no reason | 30 days, no reason | 14 days, under 10,000 calls | 90-day exit if windows are not raised | 90-day exit if windows are not raised |
The rate windows and range caps in this table are the numbers the API enforces, and they only ever go up. Enterprise keys run at the Mega windows until a load test, as above.
Who sells it, and how you pay
By card (Founding Member, Professional, API Annual Starter): payment is taken on a page Stripe hosts, and the sale is made through Link, Stripe's merchant of record. Your card statement reads LINK.COM* and the receipt says it was sold through Link. As the seller, it handles any sales tax, VAT or GST due where you are.
By invoice (API Annual Starter on request, Growth, Scale, Enterprise and the pilot): CycleCalcs LLC, a Virginia limited liability company, is the seller and sends the invoice, payable on receipt by card (ACH Direct Debit and bank transfer once enabled), with a W-9 on request. A purchase order is accepted as the order; the key is issued within 1 business day of payment.
We may decline or refund any order, and will for a buyer in a category we do not serve.
Questions
Is anything that is free today going to cost money?
No. Every calculator, every widget, the API's Basic tier without a key and the MCP server up to 50 keyless calls a day per network address stay free. A paid option adds capacity, service terms, documents and widget licenses; no tier changes an answer.
Do paid keys get different data?
No. Every tier serves the same endpoints, the same precision and the same answers. The values we compute are public domain for everyone, paid or not, under the site license, so a paid option sells capacity, service terms, files and delivery. It never sells data rights.
Is there a service level?
Keys sold for a term (API Annual, Enterprise and the pilot) carry a 99.5% monthly availability commitment, with credits as extra days on the key. Founding Member and Professional keys see the same target without credits. The free tier has no service level.
Questions about any of this: info@cyclecalcs.com. Draft of 9 October 2026.