Free resource
System design interview
template
A repeatable framework for tackling any system design question. Use this template to structure your thinking and communicate clearly.
Clarify requirements (5 min)
Don't start designing until you understand the problem. Ask:
- • Functional requirements: What should the system do? Core features vs nice-to-haves.
- • Scale: How many users? Requests per second? Data volume?
- • Consistency vs availability: What's the tolerance for stale data? What happens during failures?
- • Latency: What's acceptable response time?
Pro tip: Write down the requirements as you go. Reference them when making trade-offs later.
High-level design (10 min)
Sketch the major components and how they interact:
- • API design: Key endpoints, request/response shapes
- • Data flow: How does data move through the system?
- • Storage: What needs to be persisted? SQL vs NoSQL?
- • Core services: What are the main components?
Client → Load Balancer → API Gateway → Services → Cache → Database
Deep dive (15-20 min)
Pick 2-3 areas to explore in detail. Common deep dives:
Database schema
Tables, indexes, partitioning strategy
Caching layer
What to cache, invalidation, eviction
Scaling strategy
Horizontal vs vertical, sharding
Failure handling
Retries, circuit breakers, fallbacks
Pro tip: Let the interviewer guide which areas to explore. They'll often hint at what they want to discuss.
Trade-offs & alternatives (5 min)
Show you understand the decisions you made:
- • Why this database? "I chose PostgreSQL for ACID compliance, but Cassandra would give better write throughput if we relax consistency."
- • What would you change at 10x scale? Be ready to evolve the design.
- • What are the failure modes? Single points of failure, blast radius.
Wrap up (2 min)
Summarize and invite questions:
- • Recap the key components and data flow
- • Mention areas you'd explore with more time
- • Ask if they'd like to dive deeper into anything
Practice with common topics
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macOS 12+ (Monterey or later)
Apple Silicon or Intel
Windows 10/11 (64-bit)
4GB RAM minimum
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