PaperTrade
High-frequency algorithmic execution engine for equities.
Overview
PaperTrade is a low-latency trading simulation engine capable of processing thousands of ticks per second. It integrates directly with Polygon.io and Alpaca APIs to provide real-time market data and simulated execution against live order books.
Why It Exists
Existing paper trading platforms are either too slow, simulating execution at the minute level, or lock you into a heavy monolithic UI. I needed an API-first engine that could backtest and forward-test algorithmic strategies with millisecond precision without risking real capital.
Engineering Challenges
High-Throughput Race Conditions
Handling concurrent order executions when the market price swings rapidly. If two strategies attempt to execute massive block trades simultaneously, ensuring ledger consistency at high throughput required moving from standard database locks to a Redis-backed optimistic locking model.
WebSocket Data Streaming
Broadcasting live tick data to thousands of potential client connections without bottlenecking the main execution thread. Achieved by offloading Pub/Sub duties to a dedicated Redis cluster.
Core Stack
Performance
System Architecture
High-level overview of the data flow and infrastructure orchestration.
PostgreSQL for Ledger
Used PostgreSQL to guarantee ACID compliance for all simulated transactions and account balances.
FastAPI over Node.js
Chose FastAPI (Python) for the core engine to leverage the extensive quantitative finance libraries (Pandas, NumPy) natively.
Ready to scale your next idea?
These systems were built from scratch with zero compromises. I can do the same for your team.