Most Commonly Asked System Design Interview Questions

This System Design Interview Guide will provide the most commonly asked system design interview questions and equip you with the knowledge and techniques needed to design, build, and scale your robust applications, for professionals and newbies. The common request flow most applications follow from user to data and back

• Users → Edge & Gateway: Requests hit CDN/Edge first (for caching, TLS termination, basic DDoS/rate-limits), then the Load Balancer/API Gateway routes to the right service.
• Gateway → Services: The application/service layer handles business logic (auth, features, rules) and coordinates downstream calls.
• Services → Data: Reads/writes go to datastores (SQL/NoSQL/object storage/search). Hot reads may be cached; writes are validated and persisted.
• Services → Async: Non-blocking work (emails, webhooks, reindexing, heavy compute) is pushed to a queue; workers consume and update state later.
• Auth & Observability: Identity/Access checks happen at gateway/services; logs, metrics, and traces are emitted for monitoring, alerting, and audits.
• Response → User: The service returns a response via the gateway/edge; caches may be updated to speed up future requests.

Below is a list of the most commonly asked interview problems/case studies/questions in System Design interviews:

1. Content & Media Streaming

These systems handle large-scale media delivery and real-time streaming while ensuring low latency, high availability, and a smooth user experience.

• Design Netflix – Video Streaming Platform
• Design YouTube – Video Sharing System
• Design Spotify – Music Streaming System
• Design TikTok – Short Video Platform
• Design Zoom – Video Conferencing System

2. Social Networks & Community Platforms

These platforms manage user-generated content, social feeds, notifications, and engagement features at scale.

• Design Instagram – Social Media Platform
• Design Twitter – Feed & Messaging System
• Design Reddit – Community Discussion Board

3. Messaging & Real-Time Communication

These systems support low-latency chat, presence updates, delivery guarantees, and message synchronization across devices.

• Design WhatsApp – Real-Time Messaging
• Design Facebook Messenger
• Design Notification Service

4. Search, Suggestions & Ranking

These systems process user queries and return ranked, relevant suggestions by indexing, caching, and ranking algorithms.

• Design Autocomplete for Search Engines

5. Maps, Location & Ride Services

These services use GPS, routing algorithms, geospatial indexing, and live updates to provide real-time location-based operations.

• Design Google Maps – Navigation & Routing
• Design Uber – Ride Booking System
• Design Yelp / Location Review Service

6. Commerce, Ticketing & Payments

These platforms handle inventory, transactions, concurrency, order states, and secure real-time payment workflows.

• Design Amazon – E-commerce Architecture
• Design BookMyShow – Ticket Booking System
• Design UPI – Real-Time Payments

7. File Storage & Data Systems

These systems allow distributed file storage, replication, CDN caching, and consistent data availability across regions.

• Design Dropbox – Cloud Storage & Sync
• Design CDN – Content Delivery Network

8. Distributed Infrastructure Components

Core backend building blocks used to support scalability, reliability, scheduling, and security in large systems.

• Design Kafka – Distributed Message Queue
• Design Distributed Job Scheduler
• Design Rate Limiter
• Design Authentication System

9. Small Real-World System Designs

Common practical systems used to test core design thinking, object modeling, and workflow control.

• Design URL Shortener like TinyURL
• Design Parking Lot System
• Design Online Code Editor
• Design Vending Machine

Further Reads:

• Complete System Design Interview Guide
• System Design Tutorial
• Software Design Patterns