Astrodienst is the house the ephemeris built
Some of the software that calculates charts across the whole industry came out of this one company.
4 min read · Published 7 September 2026
Before the detail
Astrodienst, at astro.com, has been publishing free chart services for decades: natal charts, the extended chart selection, an atlas, ephemerides going back thousands of years, and paid interpretation reports by astrologers including Liz Greene and Robert Hand. It also maintains the Swiss Ephemeris, the calculation library a large part of the astrology software industry runs on. AsterNym is free, newer, reads eight symbolic systems instead of one, and states a single set of conventions rather than offering every option. For serious Western chart work, Astrodienst is the deeper resource. Disclosure: AsterNym is ours.
What they built that everyone uses
The Swiss Ephemeris is the reason this comparison starts with respect. It's the planetary calculation library behind a great deal of astrology software, licensed freely to other programs, and astro.com describes it as state of the art for astrological calculations. Whether or not you've used their site, you have probably read a chart their arithmetic produced.
We don't use it. Our positions come from astronomy-engine, an open library built for astronomy rather than astrology, which we chose because it's checkable against observatory data and because our birth sky page needs real astronomy anyway. Different library, same physics, and both agree to well within the precision any reading needs.
What Astrodienst is unmatched at
- Depth of options. The extended chart selection alone offers more chart types, house systems and settings than we're ever likely to build.
- Reports by named astrologers. Their shop sells long interpretation reports written by practitioners including Liz Greene and Robert Hand, sold individually. That's a different product from anything we do.
- Reference data. A 9,000-year ephemeris and an atlas, free, which working astrologers have leaned on for years.
- Institutional trust. Decades of operation, and a reputation for getting the numbers right.
Where we're the easier door
- No account to start. Their personalised services want registration; you can get a full reading here without one.
- Plain English first. Their free output is a chart and a set of tables; ours is a reading that names what it read.
- Traditions beyond the Western chart. BaZi, Zi Wei Dou Shu, Jyotish, numerology, Human Design and the tarot birth card, computed separately and shown together.
- A modern phone layout, where astro.com still carries a lot of its history in the interface.
The reports question
Astrodienst's paid reports are the closest thing in this comparison to what our free reading does: a long written interpretation of your chart. Theirs are written by well-known astrologers and sold per report; ours is free, shorter per system, and spread across eight traditions instead of going deep on one.
If you want thirty pages on your Western chart from a named astrologer, buy theirs. If you want a broad read across traditions with the method stated, ours costs nothing to try first.
Who should use which
Studying astrology seriously, or needing a specific house system, a solar return in a particular style, or an ephemeris for a date in the fourteenth century? Astro.com, and it isn't close.
Wanting to know what your chart says, across several traditions, without learning to read a table first? Start here, free.
Both is fine. We'd rather you checked our numbers against theirs than took ours on trust.
Mira Hale