Meta SDE2 Interview Guide
Evidence-backed preparation playbook for Meta SDE2 interviews. 7 reported questions, top topics, difficulty breakdown, and a free assessment.
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Top Questions — Ranked by Community Votes
These 6 questions appeared most in Meta SDE2 reports. Master these first.
Design Facebook's News Feed ranking system. How do you score posts from thousands of friends and pages? Cover: candidate generation, feature extraction, ML ranking model, how you handle near-real-time freshness, and edge vs server-side ranking for mobile clients.
Design Facebook Live - a system to stream live video from one user to potentially millions of concurrent viewers with low latency. Cover: ingest pipeline, transcoding, CDN edge caching, adaptive bitrate, and how you handle a celebrity going live.
Design Instagram Stories. A story disappears after 24 hours and is shown in a ring around profile pictures. Cover: upload pipeline, storage with TTL, efficient delivery to followers, and view count tracking at scale.
Design WhatsApp's end-to-end encrypted messaging system. How do you exchange keys, store messages server-side without reading them, and handle multi-device sync? Cover the Signal Protocol basics.
Explain how React's virtual DOM diffing algorithm (reconciliation) works. Why is it O(n) instead of O(n3)? What are the assumptions it makes and when do those break down (causing performance issues)?
Given Meta's social graph, find all friend-of-friend recommendations for a user that are not already friends. Discuss BFS at scale, how to prune the search space, and how to rank recommendations by mutual friend count efficiently.