Verified: May 10, 2026. Swiss Ephemeris license pricing comes from astro.com/swisseph/swephprice_e.htm. Astrology API pricing is from our own pricing page.
TL;DR
| Attribute | Astrology API | Astrodienst |
|---|---|---|
| Product type | Managed REST API | Library license + consumer site |
| Calculation engine | Swiss Ephemeris + custom | Swiss Ephemeris (originator) |
| Public REST API | Yes | Not a public commercial API |
| Self-hosting required | No | Yes (you integrate Swiss Ephemeris yourself) |
| Endpoint count | 100+ | N/A — function library |
| House systems | 23 | All known systems |
| Response time | ~287ms | Depends on your server |
| Free tier | 50 req/mo, no card | Swiss Ephemeris under AGPL is free; commercial use requires a paid license |
| Paid plans | $11 / $37 / $99 / $399+ /mo | CHF 750 one-time first license, CHF 400 each additional, valid 99 years |
| AI interpretations | Yes (multilingual) | No |
| Languages | 9+ native | N/A (data only) |
| Output format | JSON + report formats | Function calls returning C/Python/Java data structures |
| Multi-tradition | Western, Vedic, Chinese, Hellenistic | Western + Vedic primitives via library |
| Best fit | App developers who want to ship in days | Software vendors building desktop astrology suites |
What each provider is
Astrodienst does not publish a commercial REST API for third-party developers. What they offer instead is the Swiss Ephemeris library itself, available under two licenses:
- AGPL-3.0 — free, but any software that calls the library over a network (which is essentially any web app or API) must release its full source code under AGPL.
- Professional License — paid one-time license that permits closed-source commercial use.
So the comparison is less "API vs API" and more "managed API vs self-hosted library." Both paths are valid; they serve different teams.
Pricing in detail
- Free: $0/mo — 50 requests, no credit card
- Starter: $11/mo — 1,000 requests
- Professional: $37/mo — 55,000 requests
- Business: $99/mo — 220,000 requests, all endpoints
- Enterprise: $399+/mo — custom, dedicated servers
Billing is direct. There are no marketplace fees, no credit-cost arithmetic, and no per-endpoint multipliers.
- First Professional License: CHF 750 (≈ $830 USD at May 2026 rates)
- Each additional license to the same licensee: CHF 400 (≈ $443 USD)
- License duration: 99 years
- What you get: The right to use Swiss Ephemeris in proprietary, closed-source software, plus the right to display "Swiss Ephemeris Inside" on your product
github.com/aloistr/swisseph.This is genuinely good value for a long-lived desktop astrology product: pay once, ship for the lifetime of your business, no recurring infrastructure cost beyond what you spend running your own servers. It is genuinely heavy lift for a 2026 SaaS app: you operate the math infrastructure yourself, you handle ephemeris file storage (several GB), you build your own REST layer, you write your own SDKs.
Endpoint coverage
swe_calc_ut()— planetary positions for any momentswe_houses()andswe_houses_armc()— house cusps in all known systems (Placidus, Koch, Regiomontanus, Campanus, Equal, Whole-Sign, Porphyry, Morinus, Topocentric, Alcabitius, and more)swe_fixstar_ut()— fixed-star positions and aspectsswe_get_planet_name()— including asteroids, TNOs, centaurs- Ayanamsa selection across ~20 sidereal systems
- Heliocentric, topocentric, barycentric coordinate frames
- Lunar nodes (true/mean), Lilith (true/mean/corrected), and Chiron handling
Everything else — interpretations, Arabic parts, dashas, synastry aspect tables, the AI layer — you write yourself, on top of these primitives. The library gives you raw correctness. Turning correctness into product is your job.
If you've ever wondered why APIs can build differentiated features on top of "the same" Swiss Ephemeris: this is why. The core math is shared. The product layer is where vendors compete.
Performance & accuracy
What Astrology API adds on top: optimized server-side caching of ephemeris data, edge-network distribution for low latency, derived calculations (Arabic parts, fixed stars, dashas, profections) that Astrodienst leaves to the implementer.
- Date range. Swiss Ephemeris covers roughly 13,000 BC to AD 17,000. We expose the full range. If you need pre-Christian or far-future charts (mundane research, deep electional work), both providers handle it.
- Asteroid orbits. Long-period asteroids drift; Swiss Ephemeris updates its data files periodically. Astrology API stays current on the data files automatically. Self-hosted users have to remember to update.
- Topocentric vs geocentric. Astrodienst's library lets you pick; we expose it as a parameter.
Developer experience
To ship a product on Swiss Ephemeris, you need: a C/Python/Java engineer comfortable with the library, a deployment story for the ephemeris files (large binaries, version-pinned), an HTTP layer if you want a network API, a caching strategy, and ongoing maintenance. Many serious astrology software vendors have built fantastic products this way. Many app developers under-budget the work.
When to choose Astrology API
Pick Astrology API if you need:
- A REST endpoint you can call from a JavaScript front-end, a Swift app, or a Lambda function — without operating any infrastructure
- AI interpretations built in, multilingual, no separate LLM bill
- Vedic, Chinese, and Hellenistic calculations alongside Western — covered in one API
- Sub-300ms response times globally without spinning up your own CDN
- Predictable monthly pricing in USD
- Time-to-market measured in days, not quarters
- A vendor that ships interpretive endpoints, not just astronomical primitives
It's also the right call if you simply don't want to think about Swiss Ephemeris data file updates, leap seconds, or ayanamsa configuration. We handle that. You build your app.
When to choose Astrodienst (Swiss Ephemeris)
Pick a direct Swiss Ephemeris license from Astrodienst if:
- You're building a desktop astrology application (Solar Fire, Janus, Kepler, TimePassages-class software) where calls are local and per-request API pricing doesn't fit
- You're a software vendor with a 5–20 year product horizon and the one-time license amortizes to nearly zero per-year cost
- You have engineers comfortable with C/Python and astronomical math and you want full control over precision, ephemeris range, and custom techniques not available in any managed API
- Your product must work fully offline — research tools, academic software, locally-installed astrology suites
- You're contributing to astrology research or academic publication and need full reproducibility of the underlying math
- Your legal/procurement prefers one-time perpetual licenses over recurring SaaS
A direct Swiss Ephemeris license is also the right call when your downstream product's competitive edge is something other than astrology — say, you're a wellness platform integrating natal chart features as one of many tools, and you want them on-premise. Astrodienst gives you ownership.
Migration notes
Migrating between a managed API and a self-hosted library is the rare case where the migration is mostly an architectural decision, not a code change.
FAQ
Does Astrodienst offer a public REST API I can subscribe to?
Not as of May 10, 2026. Astrodienst publishes Swiss Ephemeris as a library and sells commercial licenses for it. They do not, on astro.com or astro.com/swisseph, advertise a managed REST API with monthly pricing. If you want a REST API, you either license Swiss Ephemeris and build your own, or you consume a managed API from a vendor like us.
Is Swiss Ephemeris really the same data NASA uses?
Swiss Ephemeris is derived from NASA JPL's DE431 (and more recently DE441) planetary ephemerides, with corrections and additional features applied by Astrodienst. The orbital math is the same NASA math. The library wraps it with the conveniences astrology software needs: house cusps, ayanamsas, fixed stars, asteroid catalogs.
How much does a Swiss Ephemeris commercial license cost in 2026?
From astro.com/swisseph/swephprice_e.htm (verified May 10, 2026): CHF 750 for the first Professional License, CHF 400 for each additional license to the same licensee. Each license is valid for 99 years. At May 2026 exchange rates, that's roughly $830 USD and $443 USD respectively. This is a one-time fee, not recurring.
Can I use Swiss Ephemeris for free?
Yes, under AGPL-3.0. The catch: if your software calls Swiss Ephemeris over a network — which includes any web app, API, or SaaS — you must release your full source code under AGPL or a compatible license. Most commercial products can't accept that, which is why the Professional License exists.
Is Astrology API just a wrapper around Swiss Ephemeris?
The core planetary math is Swiss Ephemeris. Astrology API adds: 23 house systems exposed via clean API enums, 97+ Arabic parts implementations, fixed-star and asteroid conjunction logic, Vedic dasha calculations, BaZi Chinese chart calculations, AI interpretation endpoints across 9+ languages, edge-network distribution, request-based billing, SDKs in five languages, and a hosted dashboard. "Just a wrapper" is technically true for the planetary math; the product layer is substantial.
Should I trust Astrodienst's data files over a managed API's data?
Yes, and so does the managed API. Astrology API uses the official Swiss Ephemeris data files, kept current with Astrodienst's releases. The accuracy question is moot — we use their data.
