Handwritten notes · Part 13
System Design Handwritten Notes for Placements (Free PDF)
By Gaurav SharmaPublished
26 pages of handwritten-style system design notes for placements and interviews: a step-by-step answer framework, estimation, load balancers, caching, CDN, SQL vs NoSQL, replication, sharding, consistent hashing, CAP, Kafka, API design, rate limiting, microservices and reliability, plus case studies and a low-level design, with Hinglish explanations.
- Pages
- 26
- Format
- A4 PDF
- Language
- English + Hinglish
- Price
- Free by email
What's inside
24 topics, one page each
- 01How to answer a system design question, step by step
- 02Back-of-envelope estimation: QPS, storage, latency numbers
- 03Vertical vs horizontal scaling and stateless servers
- 04Load balancers: algorithms, L4 vs L7
- 05Caching strategies, eviction, stampede and penetration
- 06CDN and DNS
- 07SQL vs NoSQL and the four NoSQL types
- 08Replication, replication lag and quorums
- 09Sharding and consistent hashing
- 10CAP theorem and PACELC
- 11Message queues, Kafka and delivery guarantees
- 12API design: REST, GraphQL, gRPC, pagination, idempotency
- 13Rate limiting: token bucket and sliding windows
- 14Monolith vs microservices, API gateway, sagas
- 15Reliability: availability nines, retries, circuit breakers
- 16Security and observability basics
- 17Object storage, search indexes and real-time updates
- 18Case study: URL shortener
- 19Case study: chat app (WhatsApp)
- 20Case study: news feed
- 21Case study: video streaming (YouTube)
- 22Low-level design: parking lot in Java
- 23Interview questions with short answers
- 24Revision cheat sheet
System design interviews don't have one right answer. They test whether you can turn vague requirements into a sensible architecture and explain the trade-offs. These notes give each building block one page, then put them together in four classic case studies.
What makes these System Design notes different?
- A framework, not just facts. A 7-step way to answer any design question, with time boxes for a 45-minute round.
- Trade-offs spelled out. Every concept lists when to use it and what it costs: write-back caches lose data, sharding breaks joins, AP systems return stale reads.
- Case studies you can redraw. URL shortener, chat, news feed and video streaming, each with a diagram and the decisions interviewers probe.
- LLD included. A parking lot in Java showing abstraction, the strategy pattern and thread safety.
How should you use these System Design notes?
Learn the building blocks (pages 4 to 19) first, then practise each case study out loud with a timer, drawing the diagram from memory. Use the interview Q&A and the last page for a final revision.
This is Part 13 of the series. For the database fundamentals underneath, see the SQL and DBMS handwritten notes.
FAQ
Questions about these notes
Are these system design notes really free?
Yes. The full 26-page PDF is free; email me to request the complete PDF. Share it with friends preparing for placements.
Is system design asked in fresher placements?
Often in a lighter form: product companies ask basics like caching, SQL vs NoSQL, scaling and CAP, or a simple design such as a URL shortener, and many have a low-level design round. These notes cover both.
Which case studies are included?
URL shortener, a WhatsApp-style chat app, an Instagram-style news feed and YouTube-style video streaming, each with requirements, a diagram and the key decisions, plus a parking lot low-level design in Java.
Do I need to know a specific cloud like AWS?
No. The notes teach the concepts and name real tools (Redis, Kafka, Cassandra, S3, Nginx) as examples, so the ideas carry over to any cloud.
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