Ace Your System Design Interview
Interactive guided walkthroughs, AI coaching, spaced-repetition flashcards, mock interviews, estimation calculators, and timed practice — everything you need to prepare for system design interviews at top tech companies.
Everything You Need to Prepare
Guided Board
Step-by-step interactive walkthroughs that guide you through designing real systems with diagrams, Q&A, and calculations.
Interview Framework
A structured 6-step approach to tackling any system design interview: requirements, estimation, API, design, deep dive, trade-offs.
Flashcards + SRS
Review key concepts with browse, quiz, and spaced repetition modes. SM-2 algorithm tracks your learning progress.
AI Design Coach
Chat with an AI that acts as a senior staff engineer. Supports OpenAI and Anthropic APIs.
Estimation Calculator
Interactive back-of-envelope calculators for QPS, storage, bandwidth, server count, and cache sizing.
Mock Interview
Simulate a real 45-minute interview with structured phases, tips, and note-taking for each stage.
Architecture Templates
Reusable architecture patterns: three-tier, microservices, event-driven, CQRS, serverless, and more.
Design Patterns
Essential architecture patterns with ASCII diagrams, trade-offs, and real-world examples for interviews.
Trade-offs Reference
Side-by-side comparison of key trade-offs: consistency vs availability, SQL vs NoSQL, push vs pull, and more.
Decision Trees
Interactive decision trees to choose the right database, caching strategy, and communication pattern.
Cheat Sheet
Quick reference for interviews: key numbers, database selection, caching strategies, and common patterns.
Tech Comparisons
Side-by-side comparisons: SQL vs NoSQL, Kafka vs RabbitMQ, REST vs gRPC, TCP vs UDP, and more.
Timed Quiz
Test your knowledge with a configurable quiz. Filter by category and difficulty, then self-grade.
Problem Guides
Detailed written walkthroughs for common system design problems with key decisions and pitfalls.
Diagram Builder
Interactive canvas to practice drawing system design diagrams. Drag components, connect them, and export as PNG.
Capacity Planning
Estimate QPS, storage, bandwidth, and infrastructure needs. Presets for social media, chat, e-commerce, and more.
Failure Scenarios
12 common system failures with detection, mitigation, and prevention strategies. Real-world examples included.
Scalability Playbook
10 essential scaling strategies with diagrams: caching, sharding, CDN, auto-scaling, partitioning, and more.
Microservices Guide
Communication patterns, resilience strategies, and operational patterns: API gateway, saga, circuit breaker, service mesh.
Consistency Patterns
From eventual to linearizable consistency. CAP theorem, conflict resolution strategies, quorum reads/writes.
Cheat Cards
Printable reference cards for quick review: estimation numbers, database selection, caching, load balancing.
Diagram Builder
Interactive drag-and-drop canvas to practice drawing system design diagrams with common components and presets.
Capacity Planning
Calculate QPS, storage, bandwidth, and infrastructure for any system. Presets for common systems like Twitter, WhatsApp.
Failure Scenarios
12 common failure modes with detection, mitigation, and prevention strategies. Essential for deep-dive discussions.
Scalability Playbook
10 essential scaling strategies with diagrams: caching, sharding, replication, CDN, auto-scaling, and more.
Microservices Guide
Communication patterns, resilience strategies, saga pattern, service mesh, and distributed tracing for microservices.
Consistency Patterns
From eventual to linearizable: understand consistency models, CAP theorem, conflict resolution, and quorum reads/writes.
Database Guide
Compare 8 database types with use cases, performance characteristics, and 10 common scenario recommendations.
Cheat Cards
Printable reference cards for estimation numbers, database selection, caching, load balancing, and more.
Big-O Reference
Complexity analysis for data structures, sorting algorithms, and system design operations with color-coded badges.
14-Day Study Plan
A structured 2-week learning path from fundamentals to advanced topics with daily tasks.
Popular Problems
View all →Design a URL Shortener
Design a service like TinyURL or bit.ly that shortens long URLs into compact links.
Design a Rate Limiter
Design a distributed rate limiter that can throttle requests based on various criteria like user ID, IP address, or API endpoint.
Design a Notification System
Design a scalable notification system that supports push notifications, SMS, and email across millions of users.
Design a Chat System (WhatsApp)
Design a real-time messaging system similar to WhatsApp supporting 1:1 and group chats with message delivery guarantees.
Design a News Feed (Facebook/Twitter)
Design a social media news feed that aggregates and ranks posts from followed users and pages.
Design a Distributed Cache
Design a distributed caching system like Memcached or Redis that provides low-latency data access across a cluster.
How to Use This App
Guided Walkthroughs
Start with the guided board. Design systems step-by-step with diagrams, decisions, and calculations.
Study & Review
Use flashcards with spaced repetition, read concept deep-dives, and reference the cheat sheet.
Practice Under Pressure
Run mock interviews with the structured timer. Take notes for each phase and review after.
Track Progress
Follow the 14-day study plan. Track your SRS mastery, quiz scores, and overall preparation.