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 What a Session Store Does A session store maintains server-side state for authenticated users across stateless HTTP requests. The client 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
5 min read What an Access Log Service Provides Every HTTP request to a web service generates a log record. At scale, this Read article
5 min read Why PII Scrubbing Is Hard PII (Personally Identifiable Information) appears in many forms: structured fields like email addresses and SSNs, Read article
5 min read What a Consensus Log Provides A consensus log is a fault-tolerant, ordered sequence of records that all nodes in a Read article
5 min read What an Orchestrator Does A data pipeline orchestrator schedules and executes directed acyclic graphs (DAGs) of computational tasks. Each DAG Read article
