System Design Fundamentals

The System Design Primer

Everything you need to master system design from first principles. Modular chapters covering scalability, databases, caching, and more — the system design interview primer written by engineers, for engineers.

9 chapters | ~2 hr read | Free & open
01

Scalability

Performance vs scalability, latency vs throughput, and the fundamentals of building systems that grow.

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02

Availability & Consistency

CAP theorem, consistency patterns, fail-over strategies, and replication trade-offs.

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03

DNS & CDN

How domain resolution works, record types, and how CDNs push content closer to users.

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04

Load Balancing

Layer 4 vs Layer 7, routing algorithms, horizontal scaling, and reverse proxies.

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05

Databases

RDBMS vs NoSQL, ACID vs BASE, replication, sharding, federation, and denormalization.

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06

Caching

Cache layers, eviction policies, write strategies, and cache invalidation patterns.

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07

Async & Queues

Message queues, task queues, back pressure, and event-driven architecture.

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08

Communication

HTTP, TCP, UDP, RPC vs REST, and choosing the right protocol for the job.

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09

Security

Encryption, input validation, principle of least privilege, and defense in depth.

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