Building a Real-Time Stock Screener with 10x Performance Boost

One of my most rewarding projects at Internovo was building a live stock screener that dramatically improved trading decisions.

The Challenge

Our existing stock screener had major issues:

The Architecture

I designed a three-tier system:

Frontend (React)

Backend (Flask)

Cache Layer (Redis)

Performance Improvements

Technical Deep Dive

Redis Pub/Sub Implementation

python
# Flask backend publishing to Redis
import redis
import json

r = redis.Redis()

def publish_stock_data(symbol, price):
    data = json.dumps({
        'symbol': symbol,
        'price': price,
        'timestamp': time.time()
    })
    r.publish('stock_updates', data)

React WebSocket Hook

typescript
function useStockWebSocket(symbol: string) {
  const [data, setData] = useState<StockData | null>(null);
  
  useEffect(() => {
    const ws = new WebSocket('ws://localhost:5000/stocks');
    
    ws.onmessage = (event) => {
      const parsed = JSON.parse(event.data);
      if (parsed.symbol === symbol) {
        setData(parsed);
      }
    };
    
    return () => ws.close();
  }, [symbol]);
  
  return data;
}

Results

The impact was immediate:

Key Takeaways

This project taught me that the right architecture can turn an unusable tool into a profit-generating asset.