📈 Stock Broker App (Paper Trading)

A full-stack paper trading stock broker application that simulates real-time market prices, allows users to place trades, and tracks portfolio performance — all without real money.

This project was built to deeply understand how trading platforms work end-to-end: authentication, market data, order execution, and portfolio accounting.

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🚀 Features

• 🔐 User Authentication

  • Register & login with JWT-based authentication
  • Secure password hashing using bcrypt

• 📊 Live Market Simulation

  • Background market engine simulates real-time price movement
  • Configurable tick interval
  • Price history stored for charting and analysis

• 💸 Paper Trading

  • Buy & sell stocks at live simulated prices
  • Cash balance and position tracking
  • Order history with execution details

• 📈 Portfolio Dashboard

  • Cash, equity, unrealized P&L
  • Positions overview
  • Live price updates

• ⚡ Modern Frontend

  • React + Vite
  • TanStack Query for polling and caching
  • Clean, dark trading-style UI

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🧠 Why I Built This

I wanted to go beyond tutorials and build something that:

• Mimics real trading systems
• Forces me to think about data consistency, concurrency, and state
• Combines backend logic, databases, and frontend UX in a meaningful way

Trading apps are deceptively complex — this project helped me understand:

• Why “simple” trades are not simple
• How backend systems drive frontend behavior
• How real-time systems fail if one piece is missing

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🧩 Most Challenging Part

The most challenging part was implementing and debugging the real-time market engine.

Key challenges included:

• Running a background price simulation alongside a live API
• Ensuring prices, ticks, and history stayed consistent
• Debugging silent failures when routers or tables were missing
• Coordinating backend state with frontend polling

This significantly improved my debugging skills and system-level thinking.

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💡 Most Interesting Part

The most interesting part was building the market tick engine.

Watching prices:

• Seed themselves into the database
• Update continuously
• Instantly reflect in the frontend

…was the moment the app truly felt alive.

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🏗️ Tech Stack

Backend

• Python
• FastAPI
• SQLAlchemy
• PostgreSQL
• Alembic
• JWT Authentication
• Passlib (bcrypt)

Frontend

• React
• TypeScript
• Vite
• TanStack Query
• Axios

Dev / Infra

• Docker (PostgreSQL)
• Shell scripts for local development
• Git & GitHub

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🖥️ How to Run the Project (Local Development)

Prereqs

You’ll need the following installed:

• Python 3.9+
• Node.js 18+
• Docker
• npm