System Design

All Articles (49 articles)

• Consistency Models and the CAP Theorem

  System Design / System Design Fundamentals 15 min read

  Understanding consistency guarantees in distributed systems: from the theoretical foundations of CAP to practical consistency models, their trade-offs, and when to choose each for production systems.

• Distributed Consensus

  System Design / System Design Fundamentals 13 min read

  Understanding how distributed systems reach agreement despite failures—the fundamental algorithms, their design trade-offs, and practical implementations that power modern infrastructure.Consensus is deceptively simple: get N nodes to agree on a value. The challenge is doing so when nodes can fail, messages can be lost, and clocks can drift. This article explores why consensus is provably hard, the algorithms that solve it in practice, and how systems like etcd, ZooKeeper, and CockroachDB implement these ideas at scale.

• Time and Ordering in Distributed Systems

  System Design / System Design Fundamentals 19 min read

  Understanding how distributed systems establish event ordering without a global clock—from the fundamental problem of clock synchronization to the practical algorithms that enable causal consistency, conflict resolution, and globally unique identifiers.Time in distributed systems is not what it seems. Physical clocks drift, networks delay messages unpredictably, and there’s no omniscient observer to stamp events with “true” time. Yet ordering events correctly is essential for everything from database transactions to chat message display. This article explores the design choices for establishing order in distributed systems, when each approach makes sense, and how production systems like Spanner, CockroachDB, and Discord have solved these challenges.

• Failure Modes and Resilience Patterns

  System Design / System Design Fundamentals 18 min read

  Distributed systems fail in complex, often surprising ways. This article covers the taxonomy of failures—from clean crashes to insidious gray failures—and the resilience patterns that mitigate them. The focus is on design decisions: when to use each pattern, how to tune parameters, and what trade-offs you’re accepting.

• Storage Choices: SQL vs NoSQL

  System Design / System Design Fundamentals 20 min read

  Choosing between SQL and NoSQL databases based on data model requirements, access patterns, consistency needs, and operational constraints. This guide presents the design choices, trade-offs, and decision factors that drive storage architecture decisions in production systems.

• Sharding and Replication

  System Design / System Design Fundamentals 24 min read

  Scaling data stores beyond a single machine requires two complementary strategies: sharding (horizontal partitioning) distributes data across nodes to scale writes and storage capacity; replication copies data across nodes to improve read throughput and availability. These mechanisms are orthogonal—you choose a sharding strategy independently from a replication model—but their interaction determines your system’s consistency, availability, and operational complexity. This article covers design choices, trade-offs, and production patterns from systems handling millions of queries per second.

• Indexing and Query Optimization

  System Design / System Design Fundamentals 19 min read

  Database indexes accelerate reads by trading write overhead and storage for faster lookups. This article covers index data structures, composite index design, query planner behavior, and maintenance strategies for production systems.

• Transactions and ACID Properties

  System Design / System Design Fundamentals 22 min read

  Database transactions provide the foundation for reliable data operations: atomicity ensures all-or-nothing execution, consistency maintains invariants, isolation controls concurrent access, and durability guarantees persistence. This article explores implementation mechanisms (WAL, MVCC, locking), isolation level semantics across major databases, distributed transaction protocols (2PC, 3PC, Spanner’s TrueTime), and practical alternatives (sagas, outbox pattern) for systems where traditional transactions don’t scale.

• Load Balancer Architecture: L4 vs L7 and Routing

  System Design / System Design Fundamentals 14 min read

  How load balancers distribute traffic, terminate TLS, and maintain availability at scale. This article covers the design choices behind L4/L7 balancing, algorithm selection, health checking, and session management—with real-world examples from Netflix, Google, and Cloudflare.

• CDN Architecture and Edge Caching

  System Design / System Design Fundamentals 15 min read

  How Content Delivery Networks reduce latency, protect origins, and scale global traffic distribution. This article covers request routing mechanisms, cache key design, invalidation strategies, tiered caching architectures, and edge compute—with explicit trade-offs for each design choice.

• Caching Fundamentals and Strategies

  System Design / System Design Fundamentals 16 min read

  Understanding caching for distributed systems: design choices, trade-offs, and when to use each approach. From CPU cache hierarchies to globally distributed CDNs, caching exploits locality of reference to reduce latency and backend load—the same principle, applied at every layer of the stack.

• API Gateway Patterns: Routing, Auth, and Policies

  System Design / System Design Fundamentals 18 min read

  Centralized traffic management for microservices: design choices for routing, authentication, rate limiting, and protocol translation—with real-world implementations from Netflix, Google, and Amazon.

• Service Discovery and Registry Patterns

  System Design / System Design Fundamentals 16 min read

  How services find each other in dynamic distributed environments where instance locations change continuously. This article covers discovery models, registry design, health checking mechanisms, and production trade-offs across client-side, server-side, and service mesh approaches.

• DNS Deep Dive

  System Design / System Design Fundamentals 20 min read

  The Domain Name System (DNS) is the distributed hierarchical database that maps human-readable domain names to IP addresses. Designed in 1983 by Paul Mockapetris (RFC 1034/1035), DNS handles billions of queries per day with sub-100ms latency globally—yet its design choices (UDP transport, caching semantics, hierarchical delegation) create operational nuances that affect failover speed, security posture, and load distribution. This article covers DNS internals, resolution mechanics, record types with design rationale, TTL strategies, load balancing approaches, security mechanisms (DNSSEC, DoH/DoT), and production patterns from major providers.

• Queues and Pub/Sub: Decoupling and Backpressure

  System Design / System Design Fundamentals 24 min read

  Message queues and publish-subscribe systems decouple producers from consumers, enabling asynchronous communication, elastic scaling, and fault isolation. The choice between queue-based and pub/sub patterns—and the specific broker implementation—determines delivery guarantees, ordering semantics, and operational complexity. This article covers design choices, trade-offs, and production patterns from systems handling trillions of messages daily.

• Event-Driven Architecture

  System Design / System Design Fundamentals 21 min read

  Designing systems around events rather than synchronous requests: when events beat API calls, event sourcing vs. state storage, CQRS trade-offs, saga patterns for distributed transactions, and production patterns from systems processing trillions of events daily.

• RPC and API Design

  System Design / System Design Fundamentals 14 min read

  Choosing communication protocols and patterns for distributed systems. This article covers REST, gRPC, and GraphQL—their design trade-offs, when each excels, and real-world implementations. Also covers API versioning, pagination, rate limiting, and documentation strategies that scale.

• Rate Limiting Strategies: Token Bucket, Leaky Bucket, and Sliding Window

  System Design / System Design Fundamentals 19 min read

  Rate limiting protects distributed systems from abuse, prevents resource exhaustion, and ensures fair access. This article examines five core algorithms—their internal mechanics, trade-offs, and production implementations—plus distributed coordination patterns that make rate limiting work at scale.

• Circuit Breaker Patterns for Resilient Systems

  System Design / System Design Fundamentals 17 min read

  Circuit breakers prevent cascading failures by failing fast when downstream dependencies are unhealthy. This article examines design choices—threshold-based vs time-window detection, thread pool vs semaphore isolation, per-host vs per-service scoping—along with production configurations from Netflix, Shopify, and modern implementations in Resilience4j.

• Capacity Planning and Back-of-the-Envelope Estimates

  System Design / System Design Fundamentals 13 min read

  Capacity planning validates architectural decisions before writing code. This article covers the mental models, reference numbers, and calculation techniques that let you estimate QPS, storage, bandwidth, and server counts—transforming vague “we need to handle millions of users” into concrete infrastructure requirements.

• LRU Cache Design: Eviction Strategies and Trade-offs

  System Design / System Design Building Blocks 25 min read

  Learn the classic LRU cache implementation, understand its limitations, and explore modern alternatives like LRU-K, 2Q, ARC, and SIEVE for building high-performance caching systems.

• Unique ID Generation in Distributed Systems

  System Design / System Design Building Blocks 16 min read

  Designing unique identifier systems for distributed environments: understanding the trade-offs between sortability, coordination overhead, collision probability, and database performance across UUIDs, Snowflake IDs, ULIDs, and KSUIDs.

• Distributed Cache Design

  System Design / System Design Building Blocks 18 min read

  Distributed caching is the backbone of high-throughput systems. This article covers cache topologies, partitioning strategies, consistency trade-offs, and operational patterns—with design reasoning for each architectural choice.

• Blob Storage Design

  System Design / System Design Building Blocks 17 min read

  Designing scalable object storage systems requires understanding the fundamental trade-offs between storage efficiency, durability, and access performance. This article covers the core building blocks—chunking, deduplication, metadata management, redundancy, and tiered storage—with design reasoning for each architectural choice.

• Distributed Search Engine

  System Design / System Design Building Blocks 20 min read

  Building scalable full-text search systems: inverted index internals, partitioning strategies, ranking algorithms, near-real-time indexing, and distributed query execution. This article covers the design choices that shape modern search infrastructure—from Lucene’s segment architecture to Elasticsearch’s scatter-gather execution model.

• Distributed Logging System

  System Design / System Design Building Blocks 13 min read

  Centralized logging infrastructure enables observability across distributed systems. This article covers log data models, collection architectures, storage engines, indexing strategies, and scaling approaches—with design trade-offs and real-world implementations from Netflix (5 PB/day), Uber, and others.

• Distributed Monitoring Systems

  System Design / System Design Building Blocks 16 min read

  Designing observability infrastructure for metrics, logs, and traces: understanding time-series databases, collection architectures, sampling strategies, and alerting systems that scale to billions of data points.

• Task Scheduler Design

  System Design / System Design Building Blocks 18 min read

  Designing reliable distributed task scheduling systems: understanding scheduling models, coordination mechanisms, delivery guarantees, and failure handling strategies across Airflow, Celery, Temporal, and similar platforms.

• Sharded Counters

  System Design / System Design Building Blocks 13 min read

  Scaling counters beyond single-node write limitations through distributed sharding, aggregation strategies, and consistency trade-offs.A counter seems trivial—increment a number, read it back. At scale, this simplicity becomes a bottleneck. A single counter in Firestore supports ~1 write/second. A viral tweet generates millions of likes. Meta’s TAO handles 10 billion requests/second. The gap between “increment a number” and “count engagements for 2 billion users” spans orders of magnitude in both throughput and architectural complexity.

• Leaderboard Design

  System Design / System Design Building Blocks 16 min read

  Building real-time ranking systems that scale from thousands to hundreds of millions of players. This article covers the data structures, partitioning strategies, tie-breaking approaches, and scaling techniques that power leaderboards at gaming platforms, fitness apps, and competitive systems.

• Design Real-Time Chat and Messaging

  System Design / System Design Problems 21 min read

  A comprehensive system design for real-time chat and messaging covering connection management, message delivery guarantees, ordering strategies, presence systems, group chat fan-out, and offline synchronization. This design addresses sub-second message delivery at WhatsApp/Discord scale (100B+ messages/day) with strong delivery guarantees and mobile-first offline resilience.

• Design Search Autocomplete: Prefix Matching at Scale

  System Design / System Design Problems 18 min read

  A system design for search autocomplete (typeahead) covering prefix data structures, ranking algorithms, distributed architecture, and sub-100ms latency requirements. This design addresses the challenge of returning relevant suggestions within the user’s typing cadence—typically under 100ms—while handling billions of queries daily.

• Design Collaborative Document Editing (Google Docs)

  System Design / System Design Problems 19 min read

  A comprehensive system design for real-time collaborative document editing covering synchronization algorithms, presence broadcasting, conflict resolution, storage patterns, and offline support. This design addresses sub-second convergence for concurrent edits while maintaining document history and supporting 10-50 simultaneous editors.

• Design an Issue Tracker (Jira/Linear)

  System Design / System Design Problems 27 min read

  A comprehensive system design for an issue tracking and project management tool covering API design for dynamic workflows, efficient kanban board pagination, drag-and-drop ordering without full row updates, concurrent edit handling, and real-time synchronization. This design addresses the challenges of project-specific column configurations while maintaining consistent user-defined ordering across views.

• Design a Flash Sale System

  System Design / System Design Problems 23 min read

  Building a system to handle millions of concurrent users competing for limited inventory during time-bounded sales events. Flash sales present a unique challenge: extreme traffic spikes (10-100x normal) concentrated in seconds, with zero tolerance for inventory errors. This design covers virtual waiting rooms, atomic inventory management, and asynchronous order processing.

• URL Shortener Design: IDs, Storage, and Scale

  System Design / System Design Problems 1 min read

  A comprehensive guide to designing a scalable URL shortening service like bit.ly or TinyURL.

• Design a Cookie Consent Service

  System Design / System Design Problems 25 min read

  Building a multi-tenant consent management platform that handles regulatory compliance (GDPR, CCPA, LGPD) at scale. Cookie consent services face unique challenges: read-heavy traffic patterns (every page load queries consent status), strict latency requirements (consent checks block page rendering), regulatory complexity across jurisdictions, and the need to merge anonymous visitor consent with authenticated user profiles. This design covers edge-cached consent delivery, anonymous-to-authenticated identity migration, and a multi-tenant architecture serving thousands of websites.

• CRDTs for Collaborative Systems

  System Design / Core Distributed Patterns 19 min read

  Conflict-free Replicated Data Types (CRDTs) are data structures mathematically guaranteed to converge to the same state across distributed replicas without coordination. They solve the fundamental challenge of distributed collaboration: allowing concurrent updates while ensuring eventual consistency without locking or consensus protocols.This article covers CRDT fundamentals, implementation variants, production deployments, and when to choose CRDTs over Operational Transformation (OT).

• Operational Transformation

  System Design / Core Distributed Patterns 17 min read

  Deep-dive into Operational Transformation (OT): the algorithm powering Google Docs, with its design variants, correctness properties, and production trade-offs.OT enables real-time collaborative editing by transforming concurrent operations so that all clients converge to the same document state. Despite being the foundation of nearly every production collaborative editor since 1995, OT has a troubled academic history—most published algorithms were later proven incorrect. This article covers why OT is hard, which approaches actually work, and how production systems sidestep the theoretical pitfalls.

• Exactly-Once Delivery

  System Design / Core Distributed Patterns 17 min read

  True exactly-once delivery is impossible in distributed systems—the Two Generals Problem and FLP impossibility theorem prove this mathematically. What we call “exactly-once” is actually “effectively exactly-once”: at-least-once delivery combined with idempotency and deduplication mechanisms that ensure each message’s effect occurs exactly once, even when the message itself is delivered multiple times.

• Change Data Capture

  System Design / Core Distributed Patterns 20 min read

  Change Data Capture (CDC) extracts and streams database changes to downstream systems in real-time. Rather than polling databases or maintaining dual-write logic, CDC reads directly from the database’s internal change mechanisms—transaction logs, replication streams, or triggers—providing a reliable, non-invasive way to propagate data changes across systems.This article covers CDC approaches, log-based implementation internals, production patterns, and when each variant makes sense.

• Multi-Region Architecture

  System Design / Core Distributed Patterns 19 min read

  Building systems that span multiple geographic regions to achieve lower latency, higher availability, and regulatory compliance. This article covers the design paths—active-passive, active-active, and cell-based architectures—along with production implementations from Netflix, Slack, and Uber, data replication strategies, conflict resolution approaches, and the operational complexity trade-offs that determine which pattern fits your constraints.

• Virtualization and Windowing

  System Design / Frontend System Design 20 min read

  Rendering large lists (1,000+ items) without virtualization creates a DOM tree so large that layout calculations alone can block the main thread for hundreds of milliseconds. Virtualization solves this by rendering only visible items plus a small buffer, keeping DOM node count constant regardless of list size. The trade-off: implementation complexity for consistent O(viewport) rendering performance.

• Offline-First Architecture

  System Design / Frontend System Design 23 min read

  Building applications that prioritize local data and functionality, treating network connectivity as an enhancement rather than a requirement—the storage APIs, sync strategies, and conflict resolution patterns that power modern collaborative and offline-capable applications.Offline-first inverts the traditional web model: instead of fetching data from servers and caching it locally, data lives locally first and syncs to servers when possible. This article explores the browser APIs that enable this pattern, the sync strategies that keep data consistent, and how production applications like Figma, Notion, and Linear solve these problems at scale.

• Real-Time Sync Client

  System Design / Frontend System Design 26 min read

  Client-side architecture for real-time data synchronization: transport protocols, connection management, conflict resolution, and state reconciliation patterns used by Figma, Notion, Discord, and Linear.

• Multi-Tenant Pluggable Widget Framework

  System Design / Frontend System Design 31 min read

  Designing a frontend framework that hosts third-party extensions—dynamically loaded at runtime based on tenant configurations. This article covers the architectural decisions behind systems like VS Code extensions, Figma plugins, and Shopify embedded apps: module loading strategies (Webpack Module Federation vs SystemJS), sandboxing techniques (iframe, Shadow DOM, Web Workers, WASM), manifest and registry design, the host SDK API contract, and multi-tenant orchestration that resolves widget implementations per user or organization.

• Design a Rich Text Editor

  System Design / Frontend System Design 19 min read

  Building a rich text editor for web applications requires choosing between fundamentally different document models, input handling strategies, and collaboration architectures. This article covers contentEditable vs custom rendering trade-offs, the document models behind ProseMirror, Slate, Lexical, and Quill, transaction-based state management, browser input handling (Input Events Level 2, IME), collaboration patterns (OT vs CRDT), virtualization for large documents, and accessibility requirements.

• Design an Infinite Feed

  System Design / Frontend System Design 19 min read

  Building infinite scrolling feed interfaces that scale from hundreds to millions of items while maintaining 60fps scroll performance. This article covers pagination strategies, scroll detection, virtualization, state management, and accessibility patterns that power feeds at Twitter, Instagram, and LinkedIn.

• Design a Drag and Drop System

  System Design / Frontend System Design 26 min read

  Building drag and drop interactions that work across input devices, handle complex reordering scenarios, and maintain accessibility—the browser APIs, architectural patterns, and trade-offs that power production implementations in Trello, Notion, and Figma.Drag and drop appears simple: grab an element, move it, release it. In practice, it requires handling three incompatible input APIs (mouse, touch, pointer), working around significant browser inconsistencies in the HTML5 Drag and Drop API, providing keyboard alternatives for accessibility, and managing visual feedback during the operation. This article covers the underlying browser APIs, the design decisions that differentiate library approaches, and how production applications solve these problems at scale.