The Problem
Every trader has been here: you're staring at a candlestick chart, trying to figure out if that's a Head and Shoulders forming or just noise. You flip between three indicator panels, check RSI, squint at the MACD histogram, and still aren't sure.
I wanted a tool where I could just screenshot a chart and get a structured breakdown — patterns detected, trend direction, confidence scores, and what to watch next. No manual drawing, no subjective interpretation.
So I built KlineVision.
What It Does
Upload any K-line (candlestick) chart screenshot — A-shares, US stocks, crypto, anything — and KlineVision returns:
The analysis is powered by Google Gemini's vision model with a carefully crafted prompt that enforces structured JSON output.
The Tech Stack
Next.js 16 (App Router, TypeScript)
├── EODHD + Tushare (market data)
├── Supabase (auth + PostgreSQL)
├── Stripe (subscriptions)
├── SVG K-line renderer (server-side, zero deps)
└── 11-locale i18n (en/zh/ja/ko/es/fr/de/pt/ru/ar/hi)
A few things I'm proud of:
Pure SVG K-Line Renderer
Server-rendered candlestick charts that crawlers can see (no Canvas/WebGL). I wrote a pure TypeScript SVG string generator — zero native dependencies, works in Vercel Serverless. It draws candlesticks, MA lines, volume bars, pattern highlights, and annotations, all as SVG XML strings.
Each page has real data — historical win rates, T+5/10/20 return statistics, recent detection cases — not LLM-generated fluff. The pattern detection runs a rule-based engine on actual OHLCV data from EODHD and Tushare.
11-Language Support
Every page renders in 11 languages with proper hreflang tags. Entity content (pattern names, descriptions, FAQs) is stored as L10n objects:
name:
en: "Bullish Engulfing"
zh: "看涨吞没"
ja: "強気の包み足"
ko: "상승 장악형"
# ...
Translation is done via Gemini batch API (~$0.15 for all entities × 9 languages).
The prompt is the secret sauce — it forces Gemini to output a strict JSON schema with confidence scores, bilingual explanations, and explicit "what I can't determine from this image" sections. No hallucinated price targets.
Pattern Detection Pipeline
Beyond the screenshot analysis, there's a daily data pipeline:
Try It
The core analysis feature is free. I'd love feedback from anyone who trades or is interested in technical analysis.
What's Next
More...
Every trader has been here: you're staring at a candlestick chart, trying to figure out if that's a Head and Shoulders forming or just noise. You flip between three indicator panels, check RSI, squint at the MACD histogram, and still aren't sure.
I wanted a tool where I could just screenshot a chart and get a structured breakdown — patterns detected, trend direction, confidence scores, and what to watch next. No manual drawing, no subjective interpretation.
So I built KlineVision.
What It Does
Upload any K-line (candlestick) chart screenshot — A-shares, US stocks, crypto, anything — and KlineVision returns:
- Classic Pattern Detection — Head & Shoulders, Bullish Engulfing, Morning Star, Flags, Triangles, and 70+ more patterns with confidence scores
- Chan Theory Analysis (缠论) — Bi (笔), Duan (线段), Zhongshu (中枢), and Beichi (背驰) structure detection. If you trade Chinese markets, you know how powerful this is
- Trend Judgment — Bullish / Bearish / Sideways with strength and confidence
- Trading Signals — Contextual buy/sell/watch signals with risk notes
- Bilingual Output — Full analysis in both English and Chinese
The analysis is powered by Google Gemini's vision model with a carefully crafted prompt that enforces structured JSON output.
The Tech Stack
Next.js 16 (App Router, TypeScript)
├── EODHD + Tushare (market data)
├── Supabase (auth + PostgreSQL)
├── Stripe (subscriptions)
├── SVG K-line renderer (server-side, zero deps)
└── 11-locale i18n (en/zh/ja/ko/es/fr/de/pt/ru/ar/hi)
A few things I'm proud of:
Pure SVG K-Line Renderer
Server-rendered candlestick charts that crawlers can see (no Canvas/WebGL). I wrote a pure TypeScript SVG string generator — zero native dependencies, works in Vercel Serverless. It draws candlesticks, MA lines, volume bars, pattern highlights, and annotations, all as SVG XML strings.
Each page has real data — historical win rates, T+5/10/20 return statistics, recent detection cases — not LLM-generated fluff. The pattern detection runs a rule-based engine on actual OHLCV data from EODHD and Tushare.
11-Language Support
Every page renders in 11 languages with proper hreflang tags. Entity content (pattern names, descriptions, FAQs) is stored as L10n objects:
name:
en: "Bullish Engulfing"
zh: "看涨吞没"
ja: "強気の包み足"
ko: "상승 장악형"
# ...
Translation is done via Gemini batch API (~$0.15 for all entities × 9 languages).
The prompt is the secret sauce — it forces Gemini to output a strict JSON schema with confidence scores, bilingual explanations, and explicit "what I can't determine from this image" sections. No hallucinated price targets.
Pattern Detection Pipeline
Beyond the screenshot analysis, there's a daily data pipeline:
- Fetch — Pull OHLCV data from EODHD (US/A-shares) and Tushare (HK)
- Detect — Rule-based engine scans for 10 candlestick patterns (Hammer, Engulfing, Doji, Morning/Evening Star, etc.)
- Backfill — Calculate T+5/10/20 returns for historical detections
- Compute — MACD, RSI, Bollinger Bands snapshots for each stock
- Aggregate — Win rate statistics at global/market/symbol level
Try It
- Upload a chart: klinevision.ai
- Browse patterns: klinevision.ai/patterns
- Check a stock: klinevision.ai/stocks/us/AAPL
- Scan for patterns: klinevision.ai/scanner/doji/us
The core analysis feature is free. I'd love feedback from anyone who trades or is interested in technical analysis.
What's Next
- More chart patterns in the rule engine (currently 10, targeting 30+)
- Multi-timeframe confirmation (daily + 4h + 1h)
- Real-time pattern alerts via Telegram
- Hong Kong market expansion (Tushare rate limits are... fun)
More...