Korean Saju API — Four Pillars of Destiny, in 10 languages.

A developer-first REST API for 사주팔자 calculations. Built by a Korean Saju practitioner. Free tier · usage-based pricing · sub-50ms p95 · clean JSON.

Developer quickstart See endpoints Try on Postman

Why this exists

Dating apps

Compatibility scoring beyond Western zodiac. /compatibility returns a 0–100 score with element + branch breakdown.

Wellness & horoscope

/daily endpoint, cacheable per (day-master, date). Drop-in for push notifications and widgets.

AI assistants

Structured JSON — Ten Gods, 12 Life Stages, hidden stems, Yongshin recommendation. Easy LLM grounding.

K-content platforms

10 languages (ko, en, ja, zh, es, pt-br, vi, id, hi, th). Hanja + romanized output on every pillar.

Quickstart

curl -X POST https://saju-api.pages.dev/api/v1/calculate \
  -H "X-API-Key: sajuapi_free_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "year":  1990,
    "month": 5,
    "day":   15,
    "hour":  14,
    "gender":"M",
    "lang":  "en"
  }'

Full developer quickstart → — get a free key, then copy-paste curl / JavaScript / Python examples for every endpoint.

Endpoints (v1)

Method	Path	Purpose
POST	`/api/v1/calculate`	Four Pillars from solar birthdate
POST	`/api/v1/interpret`	Ten Gods, 12 Life Stages, Daeun, Yongshin
POST	`/api/v1/compatibility`	Two-person 0–100 score
GET	`/api/v1/daily`	Daily fortune by Day Master (cacheable)

Pricing

Tier	Daily limit	Price	For
Free	100 req/day	$0	Indie devs & POCs
Dev	1,000 req/day	$9 / month	Side projects, MVPs
Pro	Unlimited (10 RPS)	$49 / month	Production apps
Enterprise	Custom + SLA	$299 / month	Volume, dedicated support

Pricing references the 2026 astrology API market: AstrologyAPI starts $99/mo for 3M req; VedicAstroAPI ~₹3,999/mo bundle. Saju API undercuts on entry-tier and is the only Korean Saju-native API with 10-lang output.