Design Robinhood – Frontend System Design
We’ll walk through the frontend system design for Robinhood: a stock trading web app where prices move several times a second, a chart follows your finger, and a Buy button moves real money. You’ll see how live quotes travel from an exchange to a table row without melting React, how a canvas chart stays at 60fps on a year of data, and how an order ticket guarantees that one tap places exactly one order.
This question looks like a dashboard. It isn’t. The interviewer is waiting for three things most candidates miss: you never render every tick, you never do money math in floating point, and you never let a network timeout turn into a duplicate order.
Problem Statement
Design the frontend for a stock trading web app like Robinhood.
Requirements:
- A watchlist with live prices and daily change for each symbol
- A stock detail page with an interactive price chart (1D, 1W, 1M, 1Y, 5Y)
- An order ticket for market and limit orders, buy and sell
- A portfolio header showing total value and today’s change,... premium content.
