System Design for Interview Prep
You have been grinding LeetCode patterns. System design is the next layer — same thinking, different scale. These articles are written in plain language with real trade-offs, not copied bullet lists. Start with the framework, then work through the case studies.
15 articles · complements our DSA study guide
How to Approach System Design Interviews (Without Panicking)
A practical framework for system design interviews: clarifying requirements, estimating scale, sketching APIs, choosing storage, and discussing trade-offs the way real interviewers expect.
Design a URL Shortener — Complete Interview Walkthrough
Step-by-step system design for a URL shortening service like bit.ly: API design, short-code generation, database schema, caching, redirects, and scaling reads to millions per second.
Design a Distributed Rate Limiter
How to design an API rate limiter for interviews: token bucket vs sliding window, where to enforce limits, Redis Lua scripts, and handling multi-server deployments without race conditions.
Caching Fundamentals Every Interview Candidate Should Know
When to add a cache, cache-aside vs read-through vs write-through, TTL and invalidation, Redis vs CDN, and the consistency traps that catch candidates in system design interviews.
From LeetCode Patterns to Real Systems
How binary search, BFS, heaps, hash maps, and LRU cache problems map to production system design — databases, queues, caches, and load balancers explained for developers who learned DSA first.
SQL vs NoSQL — How to Choose in System Design Interviews
When to pick PostgreSQL vs MongoDB vs Cassandra in interviews: ACID, schema, joins, scale-out, and concrete examples from URL shorteners, feeds, and chat.
Load Balancing and Horizontal Scaling for Interviews
L4 vs L7 load balancers, round-robin vs consistent hashing, health checks, auto-scaling, and how to explain scaling a stateless API tier in system design interviews.
Design a News Feed (Twitter / Instagram Home Timeline)
How to design a social media news feed for interviews: fan-out on write vs fan-out on read, ranking, caching celebrity users, and storage trade-offs.
Design a Chat / Messaging System (WhatsApp / Slack DM)
System design for real-time chat: WebSockets vs polling, message storage, delivery guarantees, online presence, and group chat scaling.
API Design and REST Best Practices for Interviews
How to design REST APIs in system design interviews: resources, HTTP verbs, pagination, versioning, errors, idempotency, and rate-limit headers.
Design a Unique ID Generator (Snowflake, UUID, Auto-Increment)
How to generate globally unique IDs in distributed systems: Snowflake, UUID, database sequences, and trade-offs for system design interviews.
Message Queues and Async Processing (Kafka) for Interviews
When and how to use message queues in system design: Kafka vs RabbitMQ, pub/sub, consumer groups, ordering, and decoupling write paths in interviews.
Design a Notification System (Push, Email, SMS, In-App)
System design for notifications at scale: multi-channel delivery, templates, user preferences, queues, retries, and idempotency for interview prep.
Design a Typeahead / Autocomplete System (Google Search Bar)
System design for search autocomplete: trie vs Elasticsearch, ranking, caching hot prefixes, and handling millions of queries per second in interviews.
Design a File Storage System (Dropbox / Google Drive)
System design for cloud file storage: upload chunking, metadata vs blob storage, sync, conflict resolution, and CDN delivery for interviews.
Suggested reading order
- How to Approach System Design Interviews — learn the 45-minute framework first
- Design a URL Shortener — classic case study end to end
- Caching Fundamentals — you will need this on almost every design
- Design a Rate Limiter — distributed state and atomicity
- From LeetCode Patterns to Real Systems — connect what you already know
- SQL vs NoSQL — pick the right store for each component
- Load Balancing and Horizontal Scaling — scale the app tier correctly
- Design a News Feed — fan-out on write vs read and the celebrity problem
- Design a Chat / Messaging System — WebSockets, delivery, and groups
- API Design and REST Best Practices — endpoints interviewers expect you to name
- Design a Unique ID Generator — Snowflake, UUID, and when to use each
- Message Queues and Async Processing — Kafka, ordering, and idempotent consumers
- Design a Notification System — push, email, SMS, and idempotency
- Design Typeahead / Autocomplete — trie, ranking, and hot-prefix caching
- Design File Storage (Dropbox) — chunked upload, metadata vs blobs, sync