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Side project

Paper trading platform

Practice trading Indian stocks, US stocks and crypto with real prices and simulated fills. An API server with a live matching engine, and an Android app.

Built with
  • TypeScript
  • Fastify
  • Drizzle ORM
  • PostgreSQL
  • Expo
  • React Native
Links
Code is in a private repository

What I built

  • The matching worker keeps open orders in memory and only touches the database when an order changes, fills or expires, so the hosted database can sleep when idle.
  • Each account has one market and one currency, with margin, blocked funds and charges worked out the way a broker would.
  • Invite-only sign-up, with owner and admin roles for managing users.