YOUR BRIEF
What to work through
Work through a local delivery service as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- See which items can be delivered to my location within 1 hour
- Order several items at once
- Assign a courier to each order
- Track the courier in real time until delivery
BEFORE YOU START
Constraints to discuss
- Availability answers in under 100 ms
- Strong consistency on orders: two customers never buy the same unit
- 10 million orders a day across 10,000 distribution centers
- About 20,000 availability queries a second
Need a starting point?
Watch for these common gaps as you prepare:
- Straight-line distance as the delivery test
- Checking stock and writing the order in separate steps without a transaction
- Inventory and orders in different stores held together by a lock
- A cache that is never cleared on order, so sold-out items stay listed
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.
- Meta: Prepfully lists “Design an app for food delivery similar to DoorDash” as asked of engineering managers and program managers interviewing at Meta, Disney and TikTok; not reported for software engineers.
- Deliveroo: Prepfully lists “Design a food delivery system for Deliveroo” as asked of machine learning engineers at Deliveroo.