System Design · Senior
System Design Cheat Sheet Pack
CAP, scaling, caching, queues, back-of-envelope math and the framework for any design interview.
The vocabulary and numbers behind every system design answer, plus a repeatable structure for the 45 minutes.
- Questions
- 360
- Topics
- 20
- Pages
- 246pages
- 360 questions, every one with a model answer
- Scalability & reliability cheat sheet
- Back-of-envelope formulas
- The 6-step answer framework
Get the System Design Cheat Sheet Pack — $9
One-off. Delivered as a PDF by email the moment payment clears.
Prices shown are a USD base. Your local-market price is calculated at checkout in your own currency, plus any local sales tax.
What is inside
20 chapters, in the order the interviews tend to ask them:
- Clarifying requirements and fixing the scope
- Back-of-the-envelope estimation
- Capacity planning, headroom and the scaling decision
- Latency, percentiles and the long tail
- Horizontal scaling and keeping services stateless
- Load balancing, health checks and traffic routing
- Partitioning, sharding and distributing the data
- Replication, failover and leader election
- Consistency models, CAP and choosing your guarantee
- Transactions, sagas and making retries safe
- Relational data modelling, indexes and query plans
- Document stores, wide columns and storage engines
- Caching layers and keeping cached data honest
- Message queues, event streams and asynchronous decoupling
- Rate limiting, backpressure and load shedding
- Reliability objectives and resilient call patterns
- Observability and debugging distributed systems
- Deployment strategy, migrations and backwards compatibility
- Failure modes and resilience engineering
- Delivering the design interview answer
How the answers are built
Each chapter opens with the checklist the question is really testing. A few from this pack:
- A requirement you can test is a number or an observable behaviour, never an adjective.
- Convert users to requests, then requests to storage and bandwidth, one step at a time.
- Plan for peak, not average; averages hide the only hour that matters.
- The ninety ninth percentile, not the mean, is what your slowest users feel.
- Stateless means any request can go to any instance, not that the service has no state.
- A health check that only proves the process is up will route traffic to an unready service.
Questions this pack covers
- How do you decide what to leave out of scope?
- What questions do you ask before drawing any boxes?
- How do you estimate daily requests for a two million user product
- What is Little's law and how does it size your fleet
- How do you choose a target utilisation for a service fleet?
- What headroom do you keep and how do you justify it?
- Why do you design against the ninety ninth percentile rather than the mean
- How does coordinated omission distort a latency measurement
Each one is answered in full in the pack, with the reasoning written out rather than a bullet list.
About this pack
- How many questions?
- 360, spread across 20 topics, written out in full across 246 pages.
- Do the answers just list keywords?
- No. Each answer is written as prose, because that is what you have to reproduce when someone asks you the question.
- How do I get it?
- Pay once and the PDF arrives by email immediately, with a signed download link.
- Can I get it refunded?
- Yes, if it is not what you expected. See the refund policy.
