Comparison · Updated June 2026

Astrologer vs Sirius / Kepler

Sirius and Kepler, from Cosmic Patterns Software, are among the most feature-dense professional astrology programs available — enormous interpretive report libraries, research and statistical tools, and broad technique coverage, with Sirius as the flagship and Kepler the step below. They are paid Windows desktop programs. Astrologer brings the same Swiss Ephemeris accuracy and the everyday professional techniques to any browser, free, with AI interpretation built in.

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Sirius / Kepler at a glance

Cosmic Patterns’ flagship professional Windows programs, known for vast report and research libraries.

Maker	Cosmic Patterns Software (USA), led by David Cochrane — makers of Kepler and the flagship Sirius.
Platforms	Windows desktop only (Mac via emulation). No native web or mobile.
Pricing	A one-time desktop license per program, with additional paid report and module add-ons. Check the maker’s site for current pricing.
Calculation engine	Swiss Ephemeris.
Best for	Professional and research-minded astrologers on Windows who want exhaustive reports and statistical tools.

Feature comparison

Feature	Astrologer	Sirius / Kepler
Vast interpretive report library	AI + interpretation	Yes — its hallmark
Research / statistical tools	Limited	Yes — a real strength
Runs in any browser, any device	Yes	No — Windows install
Works fully offline	Needs a connection	Yes — once installed
One-time license vs free core	Free core / $7.99 Pro	One-time paid license + add-ons
AI readings from your chart	Yes (Pro)	No — fixed report text
Astrocartography + relocation	Yes	Yes
Profections, progressions, returns	Yes	Yes — extensive
Synastry + composite	Yes	Yes
Live sessions + community + Academy	Yes	No
Calculation engine	Swiss Ephemeris	Swiss Ephemeris

Where Sirius / Kepler wins

Among the largest interpretive report libraries in any astrology software.
Genuine research and statistical tooling that few other programs match.
A dedicated, deeply customizable desktop program that works fully offline.

Where Astrologer wins

Runs in any browser on any device — no Windows, no install, no license key.
A free core, versus a paid desktop license plus paid report add-ons.
Live AI readings generated from your specific chart, instead of a fixed report library.
Cloud-saved charts, practitioner sessions, a community, and a built-in Academy.

The bottom line

If you want the deepest report libraries and real research tooling on Windows, Sirius and Kepler are hard to beat. If you want the same Swiss Ephemeris accuracy on any device — with AI readings, interpretation, and nothing to install or pay for to start — Astrologer covers the everyday professional work for free.

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Frequently asked questions

What is the difference between Sirius and Kepler?

Both are Cosmic Patterns programs; Sirius is the flagship with the most features, and Kepler is the step below it. Astrologer compares favorably to both for everyday browser-based work, while they go deeper on reports and research tools.

Is Astrologer a free alternative to Sirius or Kepler?

Largely, yes. Astrologer uses the same Swiss Ephemeris and covers most everyday professional techniques for free in the browser, though Sirius and Kepler go deeper on report libraries and statistical research.

Do Sirius and Kepler run on Mac?

They are Windows programs and typically need emulation on a Mac. Astrologer runs in any browser, so Mac, Windows, Linux, tablets, and phones all work natively.

Does Astrologer have research tools like Cosmic Patterns software?

Not to the same degree — statistical research is a genuine strength of Sirius and Kepler. Astrologer focuses on chart work, timing, interpretation, and AI readings rather than statistical research.