System Design

⏱ 6 min read Object Types A version control system stores three object types in a content-addressed object store: Blob: raw file content. The […] Read article

⏱ 6 min read Data Model: Shapes A whiteboard is a collection of shapes. Each shape is a flat record: { id: “uuid”, type: Read article

⏱ 6 min read Pull Request Model A pull request (PR) represents a request to merge a source branch into a target branch. Core Read article

⏱ 5 min read Double-Entry Ledger A digital wallet service is built on a double-entry ledger: every financial event creates exactly two entries — Read article

⏱ 6 min read Escrow Model An escrow service acts as a neutral third party: the buyer transfers funds to a platform-controlled escrow account, Read article

⏱ 6 min read Tax Service Components A production tax calculation service has five distinct responsibilities: nexus determination (does the business owe tax in Read article

⏱ 6 min read Ride Matching Service Low-Level Design A ride matching service connects riders with nearby drivers in real time, computing ETAs, scoring Read article

⏱ 6 min read Interview Scheduling System Low-Level Design An interview scheduling system matches candidate time preferences against interviewer availability, handles calendar integration, prevents Read article

⏱ 6 min read Knowledge Graph Overview A knowledge graph stores entities (people, organizations, places, events) and the typed relationships between them, enabling structured Read article

⏱ 6 min read Search Indexer Overview A search indexer transforms raw documents into a data structure that supports fast full-text queries. The pipeline Read article

⏱ 6 min read Spam Detection System Overview Spam detection combines fast rule-based velocity checks, text classification, and graph-based account analysis. No single signal Read article

⏱ 6 min read Abuse Detection System Overview An abuse detection system protects users and the platform from account takeover, credential stuffing, scraping, fake Read article

⏱ 6 min read Search Ranking System Overview A search ranking system determines the order in which retrieved documents are presented to users. The Read article

⏱ 5 min read Personalization Engine Overview A personalization engine ranks content by predicted user interest rather than global popularity. The core idea: represent Read article

⏱ 5 min read Two-Token Architecture Modern authentication uses two token types with different properties: Access token: Short-lived (15 minutes), self-contained JWT. Resource servers Read article