Astrolog

What it is

Astrolog, a free open-source astrology software developed since 1991 by Walter D. Pullen. Written in C; runs on Windows, Linux, Unix, Mac. Version 7.40+ (through 2026). Astrolog's unique side: despite being entirely free, technical depth approaching Solar Fire. Every classical technique (fixed stars, harmonics, asteroids, dwadasamsa) is supported. An astrology teacher's recommended free starter. Advantage: with source code open, programmer-astrologers can customize it for their own research. Disadvantage: interface is raw — not as polished as modern Solar Fire. But this gives it a "made just for the astrologer" feel.

Why it matters

The infrastructure of open-source astrology research — programmer-astrologers wanting customization base it on Astrolog. The "no payment required" face of modern astrology.

Themes

• open source
• free
• C code
• deep technical