LinkedIn System Design (Feed & Graph Architecture)
Design a professional networking platform like LinkedIn that allows users to create profiles, connect with other professionals, post updates, search for jobs, and message connections. The system should handle millions of users and complex relationship graphs.
Constraints
Profiles, connections (send/accept, network), feed from connections and companies, messaging, job postings and search, recommendations (connections/jobs/content), search people/companies/jobs, company pages, endorsements
1B users, billions of connections, profile/feed < 200ms, 99.9% uptime, fast search, real-time messaging and notifications
1B users, 100M DAU; ~500 connections/user → 500B connections; 10M posts/day, peak ~200/s; 100M messages/day, peak ~2K/s; 10M active jobs; ~10 TB profiles, ~50 TB connections, ~20 GB/day posts