Amazon System Design Interview: Product Page Recommendations

The interviewer opens

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

The problem is about product page recommendations, the kind of "also bought" and "recommended for you" sections shoppers see on Amazon. It's up in the Problem tab, so please read through it and ask anything you'd like clarified before you start drawing.

The problem

Design the 'customers who bought this also bought' and 'recommended for you' sections on Amazon product pages, based on what each shopper and similar shoppers have done, so they reflect recent activity and load quickly on every page view.

Must do

• Show items frequently bought together with the product being viewed
• Show each signed-in shopper a personalized 'recommended for you' list
• Recommendations reflect the shopper's recent views and purchases
• Signed-out shoppers still see sensible recommendations

Must hold

• Recommendations must load fast enough not to slow down any product page
• Shopper activity must show up in recommendations soon after it happens