About Kerykeion
Kerykeion started in 2020 as a side project.
I wanted to build a complete open-source astrology library that could provide scientifically accurate astronomical data, generate clear charts and remain simple enough for developers to use.
At the time, I could not find a modern open-source tool that brought these features together. Building a complete astrology application meant combining several libraries, filling in missing functionality and solving many of the same technical problems from scratch.
Kerykeion began as my attempt to create that missing foundation.
Since then, the project has grown beyond the original Python library. Today it includes developer tools, cloud software for astrologers and a large knowledge base covering astrology, tarot and crystals.
The original idea still guides my work: accurate calculations, transparent methods and tools that make complex information easier to understand and use.
Data-driven astrology
My approach to astrology begins with a clear distinction between astronomical data and astrological interpretation.
Planetary positions, aspects, house cusps, degrees, ingresses and retrograde dates can be calculated. Their symbolic meaning belongs to interpretation.
Data-driven astrology means treating each part according to its nature. Astronomical information should be computed accurately, the methods used to calculate it should be open to inspection, and recurring astrological ideas should remain open to observation, comparison and statistical research.
Interpretation requires a different kind of care. It involves symbols, context and different schools of thought. The guides on this site aim to explain that material clearly while respecting its interpretive nature.
Reliable computation gives the rest of the work a solid starting point.
Today, the Kerykeion platform includes:
- the open-source Kerykeion Python library
- the hosted Astrologer API
- Astrologer Studio, a cloud-based astrology application
- this free knowledge base of astrology, tarot and crystal guides
The Kerykeion Python library has been downloaded more than two million times from PyPI.
At the centre of the platform is LibEphemeris, a modern, high-precision ephemeris that I developed using NASA JPL data. It provides a transparent and maintainable astronomical foundation for the library, the API and the other tools in the Kerykeion ecosystem.
I am also developing the Virtual Astrologer, an astrological AI that combines the same computational foundation with a structured interpretive system.
Who is behind Kerykeion
I am Giacomo Battaglia, a software developer and astrologer.
I created Kerykeion to provide a reliable foundation for astrology software, with calculations that could be understood, inspected and reused.
The library is now used in research projects, professional tools and production applications.
It is available as free and open-source software under the AGPL-3.0 licence. Its source code, calculations and algorithms are publicly available for anyone who wants to study, verify or extend them.
Alongside the software, I curate the guides published on this website and define their editorial approach.
For editorial questions, corrections or privacy requests, you can contact me at kerykeion.astrology@gmail.com.
The Kerykeion platform
Kerykeion brings together tools for developers, professional astrologers, students and enthusiasts.
Python Library
The open-source calculation engine at the foundation of the project.
It calculates natal charts, synastry, transits, returns, composite charts, planetary positions, houses and aspects. It can also generate complete SVG charts.
Released under the AGPL-3.0 licence.
Explore the library →Astrologer API
A hosted REST API built on the same calculation engine.
It allows developers to generate charts, synastry data, transits and SVG graphics through JSON, using any programming language.
Explore the API →Astrologer Studio
Cloud-based astrology software for professional astrologers, students and enthusiasts.
It can be used to create and explore natal, synastry, composite and transit charts directly in the browser, with no installation or development knowledge required.
Open Astrologer Studio →Knowledge Base
A growing collection of free guides covering astrology, tarot and crystals.
The guides focus on symbolism and interpretation. When they include astronomical dates, positions or aspects, that information is generated by the Kerykeion engine.
Browse the guides →Each part of the platform serves a different purpose while sharing the same computational foundation and commitment to transparency.
How the content is made
Every guide follows an editorial process that combines research, AI-assisted drafting and personal review.
Research and source material
The starting point includes my personal notes, previous writings, years of study and the editorial framework described below.
When a guide requires astronomical information, I generate it with the Kerykeion engine. This includes planetary positions, aspects, degrees, house cusps, ingresses and retrograde dates.
The same calculations can be reproduced through the open-source library.
AI-assisted drafting
I use language models to organise material, compare interpretations and prepare initial drafts.
The main models used in this process are Claude Opus, Fable and Gemini 3.1 Pro.
Their input includes my notes, previous writings and the editorial framework of the site. They help me work consistently across a large and growing collection of pages while keeping the structure and terminology coherent.
Editing and publication
Before publication, I read and revise each guide.
I check astronomical references against the engine, correct factual issues, refine the interpretation and edit the language to match the style and principles of the site.
The published guides are original texts developed through this process.
Corrections
If you find an error in a calculation or a guide, please write to kerykeion.astrology@gmail.com.
Corrections and well-supported feedback are always welcome.
Editorial guidelines
Every guide follows the same general principles.
Astrology as a symbolic language
Astrology is presented as a language for exploring patterns, motivations, tensions and cycles.
Interpretations describe themes and possibilities. They leave room for individual context and avoid claims of certainty about a person's character or future.
Contextual interpretation
A placement, aspect or card can express itself in several ways.
Its meaning depends on the wider context, the other elements involved and the way a person relates to that symbolism.
Difficult configurations may describe tension, effort or an area of development. Harmonious configurations may describe natural abilities, familiar patterns or resources that require conscious use.
Functions rather than labels
Astrological placements are described through functions, needs, tensions and developmental themes.
The purpose is to explore what a symbol brings into the chart and how it may operate, rather than reduce a person to a fixed collection of traits.
Explanation before advice
Each guide begins by explaining the symbolism and internal logic of its subject.
Practical suggestions follow from that explanation and remain general. Medical, legal and financial advice falls outside the scope of the site.
Constructive language
The writing avoids fatalistic ideas of punishment, curses or unavoidable negative outcomes.
Traditional terminology may appear when it is useful for understanding the history of an idea. Interpretations are framed in a way that supports reflection rather than fear.
Facts and interpretation
Positions, dates, degrees, aspects and astronomical cycles are calculated data.
Their astrological meaning is interpretive.
Keeping these two levels distinct makes it easier to understand what can be verified directly and what remains open to discussion.
Original synthesis
The guides bring together historical traditions, modern interpretations, personal research and a consistent editorial method.
Their purpose is to organise complex material and explain it in a clear, accessible and useful form.
These principles apply across the astrology, tarot and crystal sections of the site.
Open source
Transparency has been part of Kerykeion from the beginning.
The Python library is released under the AGPL-3.0 licence, and its source code is publicly available on GitHub.
Developers and researchers can inspect how planetary positions, aspects, house cusps and chart results are calculated. They can reproduce the results, examine the underlying assumptions and contribute improvements.
The same computational foundation powers the Python library, the Astrologer API, Astrologer Studio and the astronomical data used throughout the Knowledge Base.
Using one shared engine keeps calculations consistent across the platform.
The goal
My goal is to make astrology software more precise, accessible and transparent, while giving astrology writing a clearer relationship with its data and methods.
For developers, Kerykeion provides complete and documented tools that can be inspected and extended.
For astrologers, it provides accurate calculations and professional charting software.
For readers, it offers a knowledge base that presents symbolic material clearly and identifies the astronomical data behind it.
You can explore the guides, calculate charts with Astrologer Studio, read the Python library documentation, or build your own application with the Astrologer API.
Contact
For editorial questions, corrections, privacy requests or general enquiries: kerykeion.astrology@gmail.com.