Meta System Design Interview: Food Delivery Orders and Dispatch

The interviewer opens

Hi, and thanks for joining. Welcome to your interview for the software engineer role at Meta. We'll design a system together, with you sketching on the whiteboard on the right of your screen as you talk. If you need to step out or take a break, you can pause the interview anytime with the Pause button at the top right.

The problem is in the Problem tab: it's a food delivery system, where orders flow between customers, restaurants and couriers. Please read through the requirements and ask me anything you'd like clarified before you start drawing.

The problem

Design a food delivery app like DoorDash: customers browse nearby restaurants and place orders, restaurants accept and prepare them, a courier is assigned to pick up and deliver, and the customer follows the order live until it arrives.

Must do

• Customers browse nearby restaurants and menus and place an order
• Restaurants receive orders, accept or reject them, and mark them ready
• A courier is assigned to each order, picks it up and delivers it
• Customer, restaurant and courier all see the order's current status as it changes

Must hold

• Status changes must reach all three parties within seconds
• An order must never be lost, double-assigned, or stuck in a wrong state