⏱ 6 min read A Content Delivery Network (CDN) caches content at edge servers distributed globally — close to users — to reduce latency […] Read article

⏱ 4 min read A real-time analytics pipeline processes streams of events and makes the results available for querying within seconds — enabling live Read article

⏱ 8 min read Two-factor authentication (2FA) requires users to present two forms of evidence: something they know (password) and something they have (phone, Read article

⏱ 4 min read A full-text search engine finds documents matching a text query from a large corpus. Building search for a product catalog, Read article

⏱ 4 min read A webhook delivery system sends HTTP callbacks to external URLs when events occur in your system — Stripe sends webhook Read article

⏱ 7 min read OAuth2 is an authorization framework that lets users grant third-party applications limited access to their data without sharing passwords. OpenID Read article

⏱ 4 min read Event sourcing is a persistence pattern where the state of an entity is derived by replaying a sequence of immutable Read article

⏱ 4 min read Database sharding splits a large dataset across multiple database servers (shards) to scale beyond what a single server can handle. Read article

⏱ 7 min read An API gateway is the single entry point for all client requests in a microservices architecture. It sits in front Read article

⏱ 8 min read Collaborative document editing allows multiple users to edit the same document simultaneously, with changes from all users appearing in real Read article

⏱ 7 min read A typeahead (autocomplete) service returns ranked completions for a query prefix in under 100ms. Google Search completes queries as you Read article

⏱ 3 min read A live leaderboard ranks users by score in real time — ranking millions of players by score in a game, Read article

⏱ 3 min read A session management system maintains state across stateless HTTP requests — tracking who a user is across page loads without Read article

⏱ 6 min read An ad click tracking system records every click on an advertisement, deduplicates fraudulent clicks, aggregates counts for billing, and provides Read article

⏱ 6 min read A shopping cart stores a user’s intended purchases before checkout. The design must handle: anonymous users (no account), authenticated users Read article