An honest reading, in your language.
20 languages Free basic $7 deep No signup
What is Saju?
Saju (사주, 四柱) — literally "Four Pillars" — is the Korean tradition of reading a person's birth chart through the Heavenly Stems and Earthly Branches of their year, month, day, and hour of birth. It shares roots with Chinese BaZi (八字) but carries its own interpretive conventions, refined in Korea for centuries.
This site gives you the real thing: the actual pillars, your Day Master, the Five Elements balance, the Ten Gods, hidden stems, twelve life stages, void branches, and ten-year luck cycles — not a Western horoscope dressed up in Eastern words.
What you get
- Free basic reading — Four Pillars + Day Master + Five Elements balance + a short AI narrative. Instant. No signup. Chart math runs in your browser; the AI narrative uses Cloudflare Workers and Anthropic.
- $7 Deep Reading — Everything above, plus an LLM-generated long-form interpretation that weaves the hidden stems, twelve stages, void branches, and ten-year luck cycles into a single narrative. Delivered to your inbox.
How it works
The deterministic chart math can run in your browser, but every AI narrative — including the current free reading and any future paid or custom reading — sends your birth date, local birth time, language, selected focus and applicable traditional gender setting to Cloudflare Workers and Anthropic's Claude API together with derived chart fields. City/country may be used by the free or Etsy flow when supplied. The free result keeps birth date/time and focus in the current page address so it can be reopened; reset removes them. The paused legacy Gumroad path excluded city and sent birth date/time, gender, language and focus in the checkout URL while Gumroad supplied the buyer email. Saju did not keep a second paid-checkout copy in browser storage. That path routed order/reading data through Gumroad, Cloudflare Workers, Anthropic and Resend; Etsy retains its own order and message records. We do not sell birth data or intentionally put it in analytics, advertising audiences, mailing lists or reusable training datasets. For Etsy made-to-order fulfillment, our 30-day deletion utility covers only the local raw-birth-data working directory, subject to a documented hold; it does not delete provider, transaction, email or message records. Anthropic states that standard API inputs and outputs are deleted within 30 days, with stated exceptions, and are not used for model training by default. Other providers apply their own terms.
Who runs this
Saju is operated by Hoonsi Kim (김시훈), an individual operator based in Seoul, Republic of Korea. Background in software engineering and product. The site is built and maintained as a one-person project — no team, no investors, no data farming.
Payment & delivery
Paid personalized readings are paused while we verify a checkout whose current policy permits this deliverable. No paid order should be started from this site. The legacy Gumroad → Cloudflare Workers → Anthropic → Resend route remains documented only for audit, rollback, and any valid pre-pause order. Returning with ?paid=deep does not itself verify payment. A future Etsy made-to-order purchase will follow the promise shown in its published listing; no Etsy listing is currently public.
Methodology
The chart computation is deterministic and reproducible, based on the open-source lunar-javascript library (v1.7.7), which encodes traditional Korean Saju conventions:
- Year pillar (년주): boundary at 立春 (Start of Spring, ~Feb 4), not the lunar new year
- Month pillar (월주): boundary at each 節 (節入) of the 24 solar terms
- Day pillar (일주): 60-갑자 cycle, 子時 (23:00–01:00) treated as the start of the next day (夜子時 = 翌日)
- Hour pillar (시주): 24h → 12지 mapping
- Hidden stems (지장간), 12 stages (12운성), void branches (공망), major luck cycles (대운), shen sha (신살): 천을귀인·도화·역마): all computed via the lunar-javascript EightChar interface
True solar time (真太陽時) longitude correction is not currently applied — the birth city field is used as reading context only. For minute-level precision (hour-pillar boundary cases), please consult a credentialed practitioner.
Sources & References
The interpretive vocabulary draws on the standard Korean and Chinese classical sources:
- 子平真詮 (Ziping Zhenquan) — format(格局) and favorable god(用神) framework
- 滴天髓 (Ditianshui) — five elements balance and Day Master strength
- 三命通會 (Sanming Tonghui) — comprehensive ten gods and shen sha catalogue
- 窮通寶鑑 (Qiongtong Baojian) — seasonal Day Master adjustments
This site does not claim to replace a credentialed practitioner; it is a software interpretation aimed at making the framework accessible globally.
AI Model Card
Every AI narrative, including the current free reading and paid or custom readings, is generated using:
- Model: Anthropic Claude Opus 4.8 (
claude-opus-4-8) - Configured max output tokens: 8,192
- Reproducibility: same birth + readingType → similar interpretation (LLM is stochastic; non-zero variance)
- System prompt: src/reading-prompt.js on GitHub (MIT-licensed)
- Inputs to the model: birth date and local time, applicable traditional gender setting, language and readingType (general/career/love/wealth), plus the deterministic chart structure derived by the Cloudflare Worker. City/country is included when supplied in the free or future Etsy flow; the paused legacy Gumroad path excluded it. The model context includes the applicable raw birth fields as well as the Four Pillars, Day Master, Five Elements, Ten Gods, hidden stems, twelve stages, void branches, major-luck cycles and current-year context.
The chart itself (Four Pillars, Five Elements, Ten Gods, hidden stems, 12 stages, void branches, major luck cycles, shen sha, current year pillar) is deterministic and verifiable via the open-source code. The LLM only generates the narrative interpretation layer on top.
Contact
Email: h.company.sean@gmail.com
Refund policy: /legal/refund · Terms: /legal/terms (legal pages English only)