Comparison · Updated June 2026

Astrologer vs Astrolog

Astrolog is one of the oldest free astrology programs, open-source and famously customizable, with a long lineage and a passionate technical following. Its interface is decidedly old-school and aimed at users comfortable with configuration. Astrologer covers the everyday professional techniques in a modern browser workspace, also free, with interpretation and learning tools built in.

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Astrolog at a glance

A free, open-source program with a long history and deep, technical customization.

Maker	Originally by Walter Pullen; open-source, maintained by the community.
Platforms	Cross-platform desktop builds (Windows, with Unix/other builds). No official mobile app.
Pricing	Free and open-source.
Calculation engine	Swiss Ephemeris (and its own legacy calculation options).
Best for	Technical, tinkering users who want a free, deeply configurable open-source program.

Feature comparison

Feature	Astrologer	Astrolog
Deep, technical customization	Themeable workspace	Yes — its hallmark
Open-source	No	Yes — fully open
Free to use	Free core	Yes — fully free
Runs in any browser, any device	Yes	No — desktop build
Works fully offline	Needs a connection	Yes — once installed
Modern, approachable interface	Yes	Old-school / technical
AI readings + plain-English interpretation	Yes	No — calculation only
Astrocartography + returns + profections	Yes	Astro maps; varies
Synastry + composite	Yes	Yes
Sessions + community + Academy	Yes	No
Calculation engine	Swiss Ephemeris	Swiss Ephemeris + legacy

Where Astrolog wins

Free, open-source, and famously customizable for technical users.
A long, trusted history and cross-platform desktop builds.
Works fully offline and stays fully under your control.

Where Astrologer wins

A modern, approachable interface instead of an old-school technical one.
Runs in any browser on any device — including phones and tablets, with nothing to configure.
AI readings and plain-English interpretation on top of the math.
Practitioner sessions, a community, and a built-in Academy alongside the chart tools.

The bottom line

Astrolog is a classic: free, open-source, and endlessly configurable for technically minded users who enjoy tinkering. Astrologer is the better fit if you want the same Swiss Ephemeris accuracy in a modern, mobile-friendly interface with interpretation and learning tools — also free to start.

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Frequently asked questions

Is Astrolog free?

Yes — Astrolog is free and open-source. Astrologer’s core is also free in the browser, with a $7.99/mo Pro plan for AI readings and unlimited saved charts.

Does Astrolog run in a browser?

No — Astrolog is a desktop program. Astrologer runs in any browser with nothing to install, including on phones and tablets.

Is Astrolog hard to use?

It is powerful but old-school and aimed at technical users comfortable with configuration. Astrologer aims for a modern, approachable interface while keeping professional depth.

Do Astrolog and Astrologer use the same calculations?

Both can use the Swiss Ephemeris, so planetary positions match. Astrologer adds interpretation, AI readings, and a modern interface on top.