System Design Interview Playbook

System design interviews test your ability to design systems under ambiguity, justify tradeoffs, and communicate clearly.

The only structure you need

Use the template in 04-SYSTEM-DESIGN-LIBRARY/00-System-Design-Template.md.

What interviewers expect (by level)

• Mid: a coherent architecture + basic scaling + failure handling.
• Senior: capacity planning + tradeoffs + operability + migrations.
• Staff+: multi-system tradeoffs, org constraints, long-term risk management.

Common ways candidates fail

• No requirements: architecture doesn’t match the problem.
• No numbers: can’t justify capacity.
• No failure plan: ignores partial failure.
• Buzzwords over data flows.

How to practice

• Do 1 prompt/week end-to-end (60–90 min).
• Do 2 “mini drills” (15 min) on one topic (cache, queue, storage).