Gexify 📊

Real-time Options Gamma Exposure Profiler

Gexify is a web tool for options traders that fetches live options chain data, calculates Gamma Exposure (GEX) per strike using the Black-Scholes model, and visualizes them as interactive charts — helping you identify key support, resistance, flip levels, and market volatility regimes.

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✨ Features

• Live GEX Chart — Bar chart of Call GEX (positive) vs Put GEX (negative) per strike, filtered to ±15% of spot on the backend for optimal performance
• Spot Price Line — Dashed white vertical line marking the current price on the chart
• GEX Flip Level — Cumulative GEX zero-crossing strike (dealer gamma reversal); shown as an orange dashed line + badge
• Support & Resistance Detection — Auto-identifies the peak put GEX strike (support) and peak call GEX strike (resistance)
• Market Regime Insight — Positive GEX (low vol / range-bound) or Negative GEX (high vol / directional) signal
• Term Structure Heatmap — Expiration dropdown dynamically colors dates with Emojis (🔴/🟢) and displays exact Net GEX values in Billions, giving an instant macro-view of the options flow
• Auto-Refresh Toggle — Keeps the dashboard live by silently polling background data every 60 seconds
• Async Backend — yfinance calls run in a thread pool executor so the FastAPI event loop is never blocked
• Robust Error Handling & Validation — Strict regex ticker validation, detailed API error messages, and graceful handling of closed-market periods
• Fast In-Memory Caching — Uses TTLCache to store expensive option chains for 60 seconds, preventing Yahoo Finance rate limits and dropping API response times to 0.02s
• Dark Glassmorphism UI — Clean, modern dark-mode interface built with vanilla JS + CSS featuring smooth fade-in animations

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📸 Screenshot

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🧮 How GEX Is Calculated

Uses Black-Scholes Gamma, scaled to dollar exposure:

GEX per strike:
  Γ = N'(d1) / (S × σ × √T)
  Call GEX = Γ × OI × 100 × Spot
  Put  GEX = Γ × OI × 100 × Spot × (−1)   ← negative by convention

where:
  d1  = [ln(S/K) + (r + 0.5σ²)T] / (σ√T)
  S   = Spot Price  |  K = Strike  |  T = Time to expiry (years)
  r   = Risk-free rate (4%)  |  σ = Implied Volatility
  OI  = Open Interest  |  100 = standard US contract multiplier

GEX flip level is computed by sorting strikes, taking the cumulative sum of Total GEX, and finding the first strike where the running total changes sign.

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🗂️ Project Structure

gexify/
├── app/
│   ├── main.py                    # FastAPI app setup, CORS, static mount
│   ├── api/
│   │   └── endpoints.py           # API routes (async executor wrappers)
│   ├── models/
│   │   └── gex.py                 # Pydantic models: GexDataPoint, GexResponse
│   └── services/
│       └── gex_calculator.py      # Black-Scholes gamma + yfinance pipeline
├── static/
│   ├── index.html                 # Single-page frontend
│   ├── app.js                     # Chart.js rendering + sparkline
│   └── styles.css                 # Dark glassmorphism theme
├── pyproject.toml                 # Python dependencies (uv)
└── main.py                        # Root entry point

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🚀 Getting Started

Prerequisites

• Python 3.13+
• uv package manager

Installation & Run

# Clone the repo
git clone https://github.com/vikbht/gexify.git
cd gexify

# Install dependencies
uv sync

# Start the server
uv run uvicorn app.main:app --reload

Then open http://localhost:8000 in your browser.

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🔌 API Endpoints

Method	Endpoint	Description
GET	/api/gex/{ticker}/expirations	List available options expiration dates with net GEX
GET	/api/gex/{ticker}?expiration=YYYY-MM-DD	Full GEX profile for a ticker

Example Response Fields

{
  "ticker": "SPY",
  "spot_price": 676.33,
  "gex_data": [{ "strike": 675, "call_gex": 1.2e9, "put_gex": -0.8e9, "total_gex": 0.4e9 }],
  "historical_prices": [{ "date": "09:30", "price": 678.1 }],
  "gex_flip_strike": 637.0
}

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📦 Tech Stack

Layer	Technology
Backend	FastAPI, Uvicorn
Data	yfinance, pandas, numpy, scipy
Models	Pydantic v2
Frontend	Vanilla JS, Chart.js
Styling	Vanilla CSS (Glassmorphism)
Package Mgmt	uv

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📖 Reading the Chart

Signal	Meaning
🟢 Positive GEX (green bars)	Call gamma — dealers hedge by selling rallies (suppresses upside)
🔴 Negative GEX (red bars)	Put gamma — dealers hedge by buying dips (amplifies downside)
Dashed white line	Current spot price
Dashed orange line	GEX flip level — cumulative gamma changes sign here
Support badge	Strike with the largest put GEX concentration
Resistance badge	Strike with the largest call GEX concentration
GEX Flip badge	Where cumulative GEX = 0; below spot → bearish lean, above → bullish
🛡️ Positive GEX Regime	Total GEX > 0 → vol suppressed → range-bound / choppy
🚀 Negative GEX Regime	Total GEX < 0 → vol amplified → expect large directional moves
⏱️ Auto-Refresh Toggle	When enabled, silently updates the backend data every 60 seconds
🔥 Term Structure Heatmap	Shows the Net GEX value in Billions for the next 30+ expiration dates in the dropdown

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⚠️ Disclaimer

This tool is for educational and informational purposes only. It does not constitute financial advice. Always do your own research before making any trading decisions.