Hey 👋

Just shipped Yarrow — an I Ching ("Book of Changes") divination web app that uses an LLM to write the interpretation.

Live: https://iching.lifefinetuning.com

The flow

User types a question

3 coins are tossed 6 times (the casting itself is pure logic , no AI)

The resulting King Wen hexagram (1 of 64) is identified, plus any changing-line transformation

An LLM steeped in the Wilhelm/Baynes tradition writes the reading

Responds in whatever language you asked in (English, Chinese, etc. — handled by the model)

Tech stack

Next.js 16 + Tailwind 4 + TypeScript on Vercel

Supabase (auth + Postgres + magic-link email via Resend)

Stripe (monthly $9.99 / annual $79)

DeepSeek for the AI (cheap, works well for both English and Chinese)

Resend for transactional email

PostHog for product analytics + Session Replay

Things I think are interesting

The hexagram engine is pure logic , not AI. I encode all 64 hexagrams as binary strings and look up the King Wen number.…