A low-level design walkthrough of collaborative document editing, explaining why naive last-write-wins breaks, how Operational Transforms work from first principles, and what makes concurrent text editing genuinely hard.
A low-level design walkthrough of Google Drive covering the Composite pattern for file/folder hierarchy, permission inheritance, file versioning trade-offs, and conflict resolution as a natural extension point.
From architecture to code: implement production-grade analytics pipelines, security layers, and observability for URL shorteners. Complete with Kafka streaming, rate limiting, and monitoring.
A low-level design walkthrough of WhatsApp covering message delivery states, per-recipient group tracking, store-and-forward for offline users, and the design decisions that make those two little ticks meaningful.
Three threads, one ordered sequence. This classic Microsoft SDE-2 problem looks like a mutual exclusion problem but it's actually an ordering problem, and that distinction changes everything.
Master the fundamentals of designing a production URL shortener: requirements, capacity planning, distributed ID generation, database design, and caching strategies for system design interviews.
A low-level design walkthrough of a load balancer covering round-robin, weighted, least-connections, and IP-hash algorithms, health checking, and the sticky sessions trade-off.
A low-level design walkthrough of a ride sharing service covering trip state machines, matching strategies, pricing, and real-time observer notifications for drivers and riders.
Parallelizing Pascal's Triangle reveals a deeper truth about task granularity: throwing threads at a problem doesn't always make it faster, and knowing when it will is the real skill.
A first-principles LLD walkthrough of Splitwise: expense types, balance tracking, the debt simplification algorithm, and why splitting responsibilities across ExpenseManager, BalanceSheet, and DebtSimplifier matters.
Designing and implementing a production-ready URL shortener with custom domains, analytics, and high availability.
A simple shared-list problem reveals how race conditions sneak past you, and why a read-write lock beats a plain mutex when reads dominate writes.
A low-level design walkthrough of a rate limiter covering class design, algorithm implementations (token bucket, sliding window, fixed window), and why the interface matters for testing and extensibility.
Building a production-ready rate limiter that scales across multiple servers using Redis and token bucket algorithm.
A first-principles LLD walkthrough of a parking lot system: spot types, vehicle matching, ticket lifecycle, pricing strategies, and how to handle concurrent spot allocation correctly.
A first-principles LLD walkthrough of a logging library covering logger hierarchy, log levels, appenders, formatters, and the Chain of Responsibility pattern for filter chains. Why appenders must be independent of formatters.
The framework I use to tackle system design interviews, demonstrated through designing a URL shortener from requirements to scaling strategies.
A first-principles LLD walkthrough of an ATM covering state management, transaction types, card and account entities, cash dispensing logic, and why atomicity matters even in a machine-coding exercise.
A first-principles LLD walkthrough of a vending machine using the State pattern. Covers state transitions, inventory management, payment handling, and why State beats if/else chains when behavior must vary by state.
A first-principles LLD walkthrough of Tic-Tac-Toe: board representation, player abstraction, game state machines, win-condition checking, and how to extend cleanly to NxN boards.