An Offerland course

System Design for Interviews

How to design systems in an interview: from load estimates to caches, queues and sharding. Lessons with diagrams, plus real case studies you talk through by voice with an AI interviewer.

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How a System Design Interview Works

An answer plan that gets you through any case.

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What They Check and How to Structure Your Answer Back-of-the-Envelope Estimates Explain It in Your Own Words: The Answer Plan

Scaling

Vertical, horizontal, and why a service should be stateless.

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Vertical and Horizontal Scaling CDN and Static Content Explain It in Your Own Words: Load Balancing and Statelessness

Caching

The most common answer to "what if it's slow?" and its traps.

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Caching: Where and How Invalidation and Cache Problems Explain It in Your Own Words: Caching Strategies

Databases

SQL or NoSQL, indexes, replication, and sharding.

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SQL, NoSQL, and Indexes Replication Sharding and CAP Explain It in Your Own Words: Replication and Sharding

Queues and Asynchrony

How to decouple services and survive traffic spikes.

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Message Queues Delivery Guarantees and Idempotency Explain It in Your Own Words: Idempotency

APIs, Reliability and Observability

Limiting load, handling failures, and how to see them.

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APIs and Rate Limiting Fault Tolerance and Observability Explain It in Your Own Words: Fault Tolerance

Case Study: URL Shortener

The classic almost everyone starts with.

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Walkthrough: URL Shortener Design a URL Shortener

Case Study: Rate Limiter

A small service with a lot of details.

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Design a Rate Limiter

Case Study: Notifications

Queues, delivery channels, and retries.

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Design a Notification Service

Case Study: Feeds and Follows

Push or pull, and what to do about celebrities with millions of followers.

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Walkthrough: News Feed Design a Personalized Feed

Case Study: Search Autocomplete

Prefixes, caching and milliseconds.

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Design Search Autocomplete