ChainDeck

ChainDeck (formerly Nifty OI Tracker) is a live, auto-refreshing dashboard for NIFTY 50 options traders. It pulls the option chain from NSE and turns it into signals: Open Interest buildup, Put-Call Ratio, Max Pain, Central Pivot Range, Gamma Exposure with the zero-gamma level, 25-delta risk reversal and a composite market regime that feeds a plain-language trade setup.

Recent work added a rolling ATM straddle panel, an IV vs realised volatility view on a trading-time basis (with IV percentile against saved sessions), a strike-wise OI structure chart, and configurable browser alerts. Under the hood, Max Pain uses prefix sums instead of a brute-force O(n²) scan, unusual OI flow is flagged with Welford's online algorithm, and cosine similarity over session feature vectors surfaces days that looked like today.

Intraday snapshots (about one a minute) are stored on Upstash Redis over REST, which powers the timeline chart, the 5m/15m rate-of-change figures and end-of-day session summaries, with an in-memory fallback when no database is configured. A caching Express proxy with request coalescing handles NSE's cookie and header requirements. The app is hardened with a strict Content-Security-Policy, no third-party assets, input validation, rate limiting and authenticated cron endpoints, and ships with a verification test suite.