Free Astrology API: Fine to Prototype, Risky to Ship

A free astrology API is the right start for a hackathon, a class project or a weekend prototype. It is the wrong foundation for an app that charges its users. This guide shows where the free path ends: the daily cap math, the licence that comes with free code on GitHub, and a checklist for any free astrology API key before you build on it.

Start with the address. A provider named after the word free is a keyword, not a brand: the name was picked to rank for this exact search, and a pricing page sits one click from every page. Free is how it earns the signup; the paid plan is how it earns a living. That trade is fine for a prototype and dangerous under an app with paying users. A keyword domain run by one person can close tomorrow, change its free tier overnight or vanish with its pricing page, and nothing obliges it to tell a free account first. Your users find out when the horoscope screen goes blank.

Is there a truly free astrology API?

Yes, in two forms, and neither is free once an app has paying users. The first is a hosted free tier: sign up, get a free astrology API key, call a daily allowance. The second is a free library on GitHub that you run yourself.

Hosted free tiers across the category share three traits:

• A small daily cap. Usually a few dozen to a few hundred requests a day, often with one request per second.
• One operator. Several free astrology APIs are run by one person. The service can close, change its terms or move its free tier at any time, and a paying app has no contract to point to.
• Sample data in some sandboxes. A sandbox that returns fixed sample responses proves the field names, not the calculation behind them.

Free libraries remove the cap and add two costs instead: upkeep and licence. Both are covered below.

For an app with users, the useful question is not "free or paid" but "what does my app call every day, and who is accountable for it". That is what the Western Astrology API is built for, on flat pricing with every domain on one plan.

How far does a free daily cap go in a real app?

Not far. A typical astrology app makes about two requests per active user per day: a daily horoscope and one chart, transit or compatibility call.

A modest app with 1,000 daily active users makes 2,000 requests a day, about 60,000 a month. That is past every free cap in the table, four times over at the highest one. When a free tier runs out, the next call fails, and the user sees an empty horoscope screen.

Caching helps with shared content. A daily horoscope per sign is the same for every reader, so one call can serve all of them. Personal charts, transits and compatibility are unique per user and cannot be shared.

What does a free astrology library from GitHub really cost?

Searching "free astrology api github" finds open source engines you can host yourself. The download is free. Two costs are not.

Maintenance. You own the server, the timezone database, the ephemeris data files, the house system edge cases at polar latitudes, ayanamsa conventions for Vedic charts, and every bug report your users send. A library calculates positions; it does not write interpretation text, translate it, or keep a typed spec in sync with your app.

Licence. Many free astrology engines are released under the GNU Affero General Public License (AGPL). Section 13 of the AGPL says that if you modify the program, your modified version "must prominently offer all users interacting with it remotely through a computer network" an opportunity to receive its source (AGPL v3 text). For a hosted app, that means your users.

The Swiss Ephemeris, the long-standing default library for astrology calculations, is dual licensed: AGPL or a paid Professional License. Its own licence page states that choosing the AGPL brings "the obligation to place his or her whole software project under the AGPL or a compatible license", and that the choice must be made "before any public service using the developed software is activated" (Swiss Ephemeris licence). Large companies treat this seriously: Google states that AGPL code "MUST NOT be used at Google" (Google AGPL policy).

Self-hosting wins when you need one calculation, in one domain, inside a project that is already open source. It costs more when the app is closed source, multi-domain, or has to stay accurate for years.

What can you use from RoxyAPI for free?

RoxyAPI gives away everything a developer needs to evaluate it and build the front end, before any plan:

• Live calls in the API reference. Every endpoint runs on production with no account and no key, and returns the same response a paid plan gets. Real calculations, not sample data.
• The widget builder. Preview every widget, theme and language at /widgets with no account.
• Free calculators at /tools. Birth chart, daily horoscope, compatibility, moon phase, panchang, nakshatra, Life Path, tarot, bodygraph and more, no signup.
• MIT code. The typed SDKs, the @roxyapi/ui components behind every widget, and the templates are published under the MIT licence: clone, rebrand and ship them.
• A free WordPress plugin in the WordPress.org directory, with blocks and shortcodes.

Once the app goes live, a plan starts at $39 a month, and annual Starter billing works out to $1.80 per domain per month. Every domain is included: Western astrology, Vedic astrology, forecast, human design, Chinese astrology, numerology, tarot and more.

What does a paid astrology API give you that free cannot?

Accountability for the part that is hard to keep right. RoxyAPI reads the NASA JPL DE440 ephemeris directly and is verified against NASA JPL Horizons; the method is public on the methodology page. It runs no third-party AGPL engine, so nothing in your app inherits a copyleft obligation from it.

Chart responses carry interpretation text beside the numbers, so the app has something to show a user, not just degrees. A natal chart takes one location lookup and one call:

curl "https://roxyapi.com/api/v2/location/search?q=New%20York&limit=1" \
  -H "X-API-Key: YOUR_API_KEY"

curl -X POST "https://roxyapi.com/api/v2/astrology/natal-chart" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: YOUR_API_KEY" \
  -d '{"date":"1990-07-15","time":"14:30:00","latitude":40.7143,"longitude":-74.006,"timezone":"America/New_York"}'

The first call returns latitude, longitude and timezone for the city. The second returns planets, houses, aspects, ascendant and midheaven, and each planet carries its sign, house and an interpretation with a summary.

How do you evaluate a free astrology API before you build on it?

Run six checks on any vendor, free or paid:

1. Who runs it? A named company with published terms, or one person with no contract.
2. What happens at the cap? A hard failure, a slowdown, or an upgrade path you can afford at your real traffic.
3. Real data or sample data? Call it with two known birth dates and compare against an ephemeris you trust, such as NASA JPL Horizons.
4. What is the licence? For a library, read the licence file. AGPL code inside a closed source app is a legal question, not a technical one.
5. Is there a typed spec? An OpenAPI document lets you generate clients and catch breaking changes.
6. Can you leave? Check that the data you need is in plain JSON you can map to another provider.

Frequently Asked Questions

Is there a free astrology API key?

Free astrology API keys exist on capped hosted tiers, usually a few dozen to a few hundred requests a day. RoxyAPI needs no key to try: the API reference runs live calls on production with no account. Production apps use a paid plan from $39 a month.

Is there a free astrology API on GitHub?

Yes, several open source astrology engines are on GitHub. Many use the AGPL licence, which obliges a hosted app to offer its source to users, and you own the hosting and upkeep. RoxyAPI publishes its SDKs, UI components and templates on GitHub under the MIT licence, with no copyleft obligation.

Is there a free horoscope API?

Free horoscope endpoints exist on capped tiers. RoxyAPI daily, weekly, monthly and yearly horoscopes can be tried live in the API reference with no account, and the daily horoscope runs free at /tools for readers.

Is there a free Vedic astrology API?

Free Vedic tiers exist with the same daily caps. RoxyAPI includes Vedic astrology on every plan beside Western astrology and the other domains, with kundli, panchang, dasha and KP, all testable live in the API reference before you pay.

Is a free astrology API safe for a commercial app?

It is fine for a prototype. For a paying app, check who runs it, what happens at the cap, and the licence. A capped tier from one operator can close or change terms at any time.

What is the best free astrology API for a prototype?

The one that returns real calculations, not sample data, with no signup. The RoxyAPI API reference runs every endpoint live on production with no account, so a prototype can be checked against the same data production will use.

Conclusion

A free astrology API is a good way to learn the shape of the data. It is a weak foundation for an app with paying users: the caps run out in a morning, one operator carries the risk, and free engines on GitHub carry upkeep and often an AGPL obligation.

RoxyAPI publishes everything that does not need constant upkeep under the MIT licence: the typed SDKs, the @roxyapi/ui components behind every no-code widget, and the templates. The multi-domain calculation and prediction infrastructure is what takes years to get right and constant engineering to keep right, and that is what a plan pays for. Try any endpoint live in the API reference, then start with the Western Astrology API.