Pass the System Design Interview
For engineers prepping the system-design loop.
Build the vocabulary and the trade-off intuition first, practice the back-of-envelope numbers, then rehearse a dozen canonical designs from a URL shortener to a payment system.
- Speak fluently about CAP, consistency, partitioning and consensus
- Estimate capacity and reason about trade-offs out loud
- Walk through canonical designs with a repeatable structure
The System Design Fundamentals Handbook
The building blocks and the vocabulary.
CAP Theorem & Consistency Models
Consistency vs availability under partition.
Partitioning, Sharding & Replication
How data scales horizontally.
Concurrency, Locks & Isolation Levels
Isolation levels and race conditions.
Consensus, Transactions & Coordination
Agreement: Raft/Paxos-level intuition.
Interactive Capacity Estimator
Practice back-of-envelope numbers.
Consistent Hashing Visualizer
See how keys move when nodes change.
Design a URL Shortener
A clean first design to rehearse.
Design a Rate Limiter
A focused, very common prompt.
Design a Key-Value Store
Replication + consistency in practice.
Design a News Feed
Fan-out and ranking at scale.
Design a Payment System
Consistency and ledgers where it counts.
How to walk into the room ready
The system-design interview rewards structured thinking under ambiguity: clarify the requirements, estimate the scale, sketch the components, then defend the trade-offs. This path builds that instinct with the fundamentals handbook, capacity and availability tools, and a run of real interactive system designs you can reason about end to end.
The aim isn't to memorise architectures — it's to internalise the moves (partition, replicate, cache, queue) and the trade-offs interviewers actually probe, so any prompt becomes a design you can drive rather than a blank you freeze on.