System Design Playbooks
Practice problems with the answer key interviewers expect.
Each guide follows the same flow as a LeetSys interview: define functional and non-functional requirements, identify key entities, design APIs, trace data flow, explain the architecture, and handle follow-up questions.
detailed public guides
Written for candidates who need more than a diagram: requirements, key entities, APIs, data flow, failure modes, and rubrics.
Requirements
Functional scope, non-functional goals, and scale assumptions.
Key entities
The actors, objects, fields, ownership, and relationships to model.
Tradeoffs
What to choose, when to choose it, and what can break.
Rubrics
What strong mid-level and senior answers should signal.
Problem Guides
Start with the canonical questions, then practice the follow-ups.
L4 to L5
URL Shortener
A practical system design interview guide for building a URL shortener with redirects, custom aliases, analytics, rate limits, and high availability.
L5 to L6
News Feed
A complete system design guide for building a personalized social news feed with fanout, ranking, privacy, and timeline freshness tradeoffs.
L5 to L6
Video Streaming
A senior-level guide to designing a YouTube-style video streaming system with uploads, transcoding, CDN delivery, metadata, search, and recommendations.
L5 to L6
Real-Time Chat
A practical chat system design guide covering WebSockets, message ordering, delivery receipts, offline sync, group chats, and end-to-end reliability.
L5 to L6
Ride Sharing
A system design guide for Uber-style ride matching with geospatial indexing, driver location updates, dispatch, pricing, trip state, and reliability.
L5 to L6
Ticketing Platform
A high-signal system design guide for Ticketmaster-style ticket sales with inventory holds, queues, payment, seat maps, and flash-sale traffic.
L5 to L6
File Storage Sync
A Dropbox-style system design guide for file upload, metadata, block storage, deduplication, sharing, sync conflicts, and consistency.
L4 to L5
Rate Limiter
A focused system design guide for distributed rate limiting with token buckets, sliding windows, Redis, local caches, multi-region behavior, and abuse controls.
L4 to L5
Search Autocomplete
A system design interview guide for typeahead search suggestions with tries, prefix indexes, ranking, freshness, personalization, and abuse filtering.
L4 to L5
Notification System
A useful system design guide for sending email, push, SMS, and in-app notifications with preferences, fanout, retries, deduplication, and provider failover.