Senior SDE Interview Questions at Meta

Design Instagram feed — a user follows 500 people, each posts 2-3 times daily. How do you generate and serve a personalized, ranked feed at scale?

A news feed component re-fetches and re-renders every item whenever a single like count changes. Walk through how you would restructure state so only the affected item re-renders, without introducing a global state library.

Design the "who viewed your profile" feature for a professional network with 500M users. Discuss write amplification, retention policy, and privacy controls for who can see the data.

Explain the output order of this code and why: console.log(1); setTimeout(()=>console.log(2),0); Promise.resolve().then(()=>console.log(3)); console.log(4);

Describe a situation where you had to ship a feature you personally disagreed with. How did you handle it, and would you make the same call again?

You have a Kafka topic with 6 partitions and a consumer group with 10 consumer instances. What happens to the 4 extra consumers, and why is over-provisioning consumers like this a mistake?

What is a memory leak in Java despite having a garbage collector? Give a concrete example involving a static collection.