Stocks
Royale

Built for college. There is no real market behind it. A Node backend generates the price movement, stores it in Postgres and pushes updates to the browser over a socket, and the frontend charts whatever arrives. The trading, the leaderboard and the charts are all real code, the prices are not.

Prices move faster than a chart wants to redraw, so most of the work went into deciding how often to repaint without the numbers going stale on screen.

Heads up: the backend is not always running, so the live demo may load with no data.