6 min read The technical phone screen is your first coding interview — and the highest-rejection stage (60-70% of candidates are eliminated). You […] Read article
6 min read AWS S3 stores trillions of objects with 99.999999999% durability, serving millions of requests per second. While our earlier Object Storage Read article
6 min read Electronic Health Record systems manage the most sensitive data in technology — patient medical histories, diagnoses, prescriptions, and lab results. Read article
6 min read Knowing which problems are most frequently asked at each company gives you a significant preparation advantage. This guide compiles the Read article
6 min read Twitter Direct Messages (DMs) serve hundreds of millions of users with private 1-on-1 and group conversations. Designing a DM system Read article
6 min read Blockchain explorers like Etherscan and Blockscout provide a searchable interface to blockchain data: transactions, blocks, addresses, smart contracts, and token Read article
5 min read This is the definitive cheat sheet for coding interview patterns. Each pattern is described with: when to recognize it, the Read article
6 min read Elasticsearch powers search at Wikipedia, GitHub, Stack Overflow, and Netflix, handling billions of documents with sub-second query latency. While our Read article
6 min read Twitch handles millions of concurrent live streams watched by 30+ million daily active users. Designing a live streaming platform tests Read article
5 min read System design interviews are the most anxiety-inducing part of the senior engineering interview loop. Unlike coding problems with clear right/wrong Read article
7 min read Discord serves 200+ million monthly active users across millions of servers (communities) with real-time text messaging, voice channels, video, screen Read article
6 min read Live audio platforms like Twitter Spaces and Clubhouse create real-time audio rooms where speakers broadcast to thousands of listeners. Designing Read article
5 min read Dynamic programming on strings is one of the most important and frequently tested DP categories. The pattern is consistent: define Read article
6 min read Stripe processes hundreds of billions of dollars annually for millions of merchants, handling the full payment lifecycle from card tokenization Read article
6 min read Notion is a collaborative workspace that combines documents, databases, wikis, and project management in a single tool. With 30+ million Read article
