Tag
system-design
NAT: Addresses, Ports, and Connection State
Trace packet translation and return-path state, calculate hot-destination port capacity, and design NAT egress around failure boundaries, observability, and explicit access policy.
Design a Crawl-Based Product Catalog for Advertising
Build an advertising catalog from merchant websites with polite crawling, verified offers, media ingestion, and freshness controls.
Design a Calendar and Scheduling System
Design shared events, recurring meetings, time-zone handling, reliable reminders, and incremental sync around one authoritative event model.
Design a Search Autocomplete System
Design prefix retrieval, live trends, ranking, and emergency takedowns with immutable indexes and bounded online work.
Design a Real-Time Ad Budget and Pacing System
Account for millions of impressions, filter 10,000 candidates locally, and protect shared advertising budgets with reserved quota.
IP Addresses in Production: Prefixes, Routes, and Identity
Understand IP addressing through CIDR, packet forwarding, NAT, IPv6, and the failures that appear when networks grow.
Design an A/B Testing Platform
Deterministic local assignment, reliable exposure tracking, reproducible analytics, and safe rollout controls at scale.
Design a Cloud Sandbox Platform for Untrusted Code
MicroVM isolation, durable workspaces, browser and SSH access, and resource-aware task scheduling with leases, fencing, and recovery.
Why No Architecture Is Perfect
How to compare feasible designs, recognize conflicting requirements, and revise architecture decisions as workloads and risks change.
Design a Multi-Modal Content Moderation Platform
A low-latency publishing gate, asynchronous video analysis, versioned policy decisions, human review, and reliable enforcement at scale.
The Trade-offs Behind Every System Design
How to reason about speed, freshness, durability, scale, and complexity by following where work and state move.
Design a User Behavior Data and Feature Platform
From mobile events to trustworthy sessions, funnels, offline training data, and fresh online model features.
How Much Does Big-O Matter in System Design?
Use asymptotic complexity to spot growth problems, then budget the I/O, fan-out, queues, and failures it cannot describe.
Design a Hierarchical File System with Inherited Permissions
A secure file platform with group ACLs, inherited access, SQL authorization, and safe revocation.
Design a Real-Time Multiplayer Board Game Platform
Server-authoritative turns, durable move ordering, reconnects, clocks, and safe failover for online two-player games.
Stateless vs Stateful: Where Does the State Live?
Why moving state out of a server changes scaling and failure boundaries—and when keeping state close to computation is the better choice.
Design a Real-Time Stock Price Alert System
Shared rolling price changes, sharded threshold matching, and durable one-shot alerts for millions of market subscriptions.
Design a Real-Time Restaurant Analytics Dashboard
How to serve fresh orders, revenue, and top-dish metrics at 100K order events per second without scanning raw orders.
What Scalability Really Means
How to reason about growth, bottlenecks, load distribution, partitioning, overload, and the cost of adding capacity.
The Five Constraints of System Design
A practical mental model for latency, throughput, availability, durability, and consistency—and why improving one can make another harder.
Design a Secure Enterprise Copilot API
A Staff-level design for secure Copilot chat, authorized retrieval, delegated tools, streaming, and cost control.