System Design Tutorial
Learn system design: requirements, scaling, caching, databases and consistency
Intermediate6 lessonsabout 35 min of reading
This tutorial is for developers who can already build a working application and now want to understand how to design one that keeps working under heavy traffic, survives failures and can be changed safely. It suits engineers preparing for system design interviews as well as people who simply want to make better architecture decisions at work.
Instead of memorising famous architectures, you will learn a repeatable way to approach any design problem: clarify requirements, estimate scale, choose building blocks and justify the trade-offs. You will see how load balancers, caches, databases, replication, sharding and consistency models fit together, and why every choice costs something. All numbers in the examples are illustrative assumptions for practice, not statistics about any real company.
The lessons are ordered from framework to building blocks to a complete worked example. Start with the basics of requirements and estimation, move through scalability, caching, databases and the CAP theorem, and finish by designing a URL shortener from scratch. For interview-specific strategy, pair this with the system design interview prep guide.
System Design lessons
- 1System Design Basics: How to Approach Any Design ProblemSystem design basics: separate functional and non-functional requirements, do back-of-envelope estimates and follow a repeatable 5-step framework.6 min read
- 2Scalability and Load BalancingUnderstand scalability and load balancing: vertical vs horizontal scaling, stateless services, balancing algorithms, health checks and avoiding failures.5 min read
- 3Caching: Strategies, Eviction and PitfallsLearn caching in system design: cache-aside, write-through and write-back, TTL, LRU eviction, invalidation, cache stampede and CDN usage, with trade-offs.6 min read
- 4Databases in System Design: SQL vs NoSQL, Replication and ShardingChoose between SQL and NoSQL in system design, and learn ACID vs BASE, indexes, read replicas, sharding keys and how to avoid hot partitions.6 min read
- 5CAP Theorem and Consistency ModelsUnderstand the CAP theorem and consistency models: partitions, CP vs AP systems with examples, strong vs eventual consistency and quorum reads and writes.5 min read
- 6Design a URL Shortener (Worked Example)Design a URL shortener step by step: requirements, estimation, API, base62 ID generation, schema, caching, scaling and the trade-offs behind each choice.7 min read
Ready to apply these building blocks? Work through 36 system design interview problems, from a URL shortener to a payment system, each with an architecture diagram.
Preparing for an interview? Practise System Design interview questions
Learning System Design to land a job? Browse open roles or check which skills are trending.