Twitch handles millions of concurrent live streams watched by 30+ million daily active users. Designing a live streaming platform tests […]

System design interviews are the most anxiety-inducing part of the senior engineering interview loop. Unlike coding problems with clear right/wrong

Discord serves 200+ million monthly active users across millions of servers (communities) with real-time text messaging, voice channels, video, screen

Live audio platforms like Twitter Spaces and Clubhouse create real-time audio rooms where speakers broadcast to thousands of listeners. Designing

Dynamic programming on strings is one of the most important and frequently tested DP categories. The pattern is consistent: define

Stripe processes hundreds of billions of dollars annually for millions of merchants, handling the full payment lifecycle from card tokenization

Notion is a collaborative workspace that combines documents, databases, wikis, and project management in a single tool. With 30+ million

Graph problems appear in 20% of coding interviews at top tech companies. The key challenge is recognizing that a problem

Figma is a browser-based collaborative design tool used by millions of designers, serving as a real-time multiplayer editor for vector

IoT platforms manage millions of connected devices — sensors, cameras, industrial equipment, smart home devices — collecting telemetry data and

Array problems are the most common category in coding interviews, appearing in over 40% of questions. This comprehensive guide organizes

DoorDash processes millions of food delivery orders daily, coordinating three parties: customers, restaurants, and drivers (Dashers). Designing a food delivery

Google Calendar manages billions of events for hundreds of millions of users with complex scheduling requirements: recurring events with exceptions,

String problems appear in 25-30% of coding interviews, making them the second most common category after arrays. String manipulation requires

Robinhood democratized stock trading with zero-commission trades and a mobile-first experience for 23+ million users. Designing a stock trading platform