Interview Toolkit

Master Vetora's recommended four-step approach to system design interviews: Clarify Requirements, High-Level Design, Deep Dive, and Wrap Up. Learn how to time-box each phase for a 45-minute interview and compare with other popular frameworks.

Learn how to spend the first 5 minutes of a system design interview gathering functional requirements, non-functional requirements, scale estimates, and constraints -- the foundation that determines every subsequent design decision.

The essential numbers every system design candidate should know: powers of two, time unit conversions, storage estimates, throughput benchmarks, and the back-of-envelope estimation chain from DAU to QPS to storage to bandwidth.

How to draw clear, effective architecture diagrams during a system design interview. Learn standard shapes, arrow conventions, progressive layering, and how to communicate your design visually on a whiteboard or digital canvas.

Master the #1 signal interviewers look for: the ability to reason about and articulate trade-offs. Learn the 'I chose X over Y because Z' formula, the three-option technique, and how to handle interviewer pushback gracefully.

Modern system design interviews now include cost estimation. Learn cloud pricing models, the cost estimation framework (identify the driver, estimate monthly cost, optimize), and why 'cost per request' is the key metric for microservices.

The 2026 twist: interviewers add AI/ML requirements mid-interview. Learn how to handle 'now add a recommendation engine,' 'add content moderation,' 'add a chatbot,' and 'optimize search with ML' by mastering embedding pipelines, vector databases, RAG architectures, and ML serving patterns.

A complete interview walkthrough for the URL shortener problem -- the most commonly asked system design question. Covers requirements gathering, scale estimation, API design, encoding strategies, caching, and collision handling.

A detailed interview walkthrough for designing a distributed rate limiter. Covers four algorithms (fixed window, sliding window log, sliding window counter, token bucket), Redis-based implementation, race condition handling, and placement decisions.

A comprehensive interview walkthrough for designing a social media news feed or timeline. Covers the push vs pull fanout trade-off, the celebrity problem, feed ranking, pagination, and media handling.

A thorough interview walkthrough for designing a real-time chat system like WhatsApp or Slack. Covers WebSocket transport, message storage and ordering, delivery guarantees, presence, group chat, and offline message delivery.

A detailed interview walkthrough for designing a trending topics system. Covers exact vs approximate counting, Count-Min Sketch, time-windowed aggregation, geo-partitioned trends, and anti-gaming strategies.

A modern interview walkthrough for designing a Retrieval-Augmented Generation (RAG) search system. Covers document ingestion, chunking strategies, embedding models, vector databases, hybrid search, reranking, and LLM-generated answers with citations.

A structured self-scoring rubric for evaluating your own system design interview practice sessions. Covers five dimensions -- requirements gathering, high-level design, deep dive, trade-offs, and communication -- on a 0-3 scale each, totaling 15 points.